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The relevant literature on missile defense is limited in that it primarily consists of policy-oriented prescriptive studies that support or oppose the deployment of missile defense in a host country. To address this deficiency, the current research compares two controversial cases of US missile defense deployment in Poland and the Republic of Korea. A theoretical framework is developed based on the alliance security dilemma to explain why certain allies accept US missile defense. The framework is used to evaluate two key aspects of missile defense deployment: whether a missile defense target is a shared adversary and the degree of reliance on the alliance. These variables are utilized as measures of entrapment and abandonment fears to explain why allies accept US missile defense systems. [ABSTRACT FROM AUTHOR]

Recent advances in radar seeker technologies have considerably improved missile precision and efficacy during target interception. This is especially concerning in the arenas of protection and safety, where appropriate countermeasures against enemy missiles are required to ensure the protection of naval facilities. In this study, we present a reinforcement-learning-based strategy for deploying decoys to enhance the survival probability of a target ship against a missile threat. Our approach involves the coordinated operation of three decoys, trained using the Multi-Agent Deep Deterministic Policy Gradient (MADDPG) and Multi-Agent Twin Delayed Deep Deterministic Policy Gradient (MATD3) algorithms. The decoys operate in a leader–follower dynamic with a circular formation to ensure effective coordination. We evaluate the strategy across various parameters, including decoy deployment regions, missile launch directions, maximum decoy speeds, and missile speeds. The results indicate that, decoys trained with the MATD3 algorithm demonstrate superior performance compared to those trained with the MADDPG algorithm. Insights suggest that our decoy deployment strategy, particularly when utilizing MATD3-trained decoys, significantly enhances defensive measures against missile threats. [ABSTRACT FROM AUTHOR]

The decision by South Korean authorities to deploy a Terminal High Altitude Area Defense (THAAD) missile battery in 2016 unleashed a storm of protest, both domestically and internationally. Attempts to resolve these debates by showing the 'truth' of the THAAD system obscure the considerable investment of time and resources needed to stabilize technological meanings in the face of rival interpretations. This article synthesizes work in the field of Science and Technology Studies (STS) to present an integrated model of technopolitics explaining how doing politics through 'things' consists of interlinked rhetorical, performative, and material stabilization techniques each seeking to make the object simple, nonpolitical, and ultimately invisible or banal. In the case of THAAD, the single battery deployed to South Korea was the tip of a broader US technopolitical project to materially bind together its regional allies and contain North Korea and China. However, opponents inside and outside of the Korean peninsula tried to destabilize this project by employing their own rhetorical, performative, and de-materialization strategies. This resulted in a partial victory for both sides insofar as the broader US missile defense technopolitical project on the peninsula was paused but not defeated. [ABSTRACT FROM AUTHOR]

This paper investigates interception missiles’ trajectory tracking guidance problem under wind field and external disturbances in the boost phase. Indeed, the velocity control in such trajectory tracking guidance systems of missiles is challenging. As our contribution, the velocity control channel is designed to deal with the intractable velocity problem and improve tracking accuracy. The global prescribed performance function, which guarantees the tracking error within the set range and the global convergence of the tracking guidance system, is first proposed based on the traditional PPF. Then, a tracking guidance strategy is derived using the integral sliding mode control techniques to make the sliding manifold and tracking errors converge to zero and avoid singularities. Meanwhile, an improved switching control law is introduced into the designed tracking guidance algorithm to deal with the chattering problem. A back propagation neural network (BPNN) extended state observer (BPNNESO) is employed in the inner loop to identify disturbances. The obtained results indicate that the proposed tracking guidance approach achieves the trajectory tracking guidance objective without and with disturbances and outperforms the existing tracking guidance schemes with the lowest tracking errors, convergence times, and overshoots.

Recent advances in radar seeker technologies have considerably improved missile precision and efficacy during target interception. This is especially concerning in the arenas of protection and safety, where appropriate countermeasures against enemy missiles are required to ensure the protection of naval facilities. In this study, we present a reinforcement-learning-based strategy for deploying decoys to enhance the survival probability of a target ship against a missile threat. Our approach involves the coordinated operation of three decoys, trained using the Multi-Agent Deep Deterministic Policy Gradient (MADDPG) and Multi-Agent Twin Delayed Deep Deterministic Policy Gradient (MATD3) algorithms. The decoys operate in a leader–follower dynamic with a circular formation to ensure effective coordination. We evaluate the strategy across various parameters, including decoy deployment regions, missile launch directions, maximum decoy speeds, and missile speeds. The results indicate that, decoys trained with the MATD3 algorithm demonstrate superior performance compared to those trained with the MADDPG algorithm. Insights suggest that our decoy deployment strategy, particularly when utilizing MATD3-trained decoys, significantly enhances defensive measures against missile threats.

During the Cold War, the Soviet Union invested heavily in its air defense systems, so its rightful successor, Russia, has now some of the most advanced air and missile defense systems in the world. Among them, the S-400 “Triumf” surface-to-air missile system is perhaps the most criticized, shrouded in mystery, and feared system in Russia’s arsenal. Developed and then presented as capable of engaging a variety of aerial threats, the system gained a reputation, at least declaratively, of being able to counter US and NATO ambitions to win a conflict through airspace dominance.

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The paper provides a comparative analysis study of the dynamics and mechanisms of the strategic stability transformation both during the Cold War and at present. Drawing on the analysis of the factors affecting strategic stability in different time periods, the author outlines the priorities of this transformation. Its basic principles are confined to the stability of nuclear deterrence in any realistic scenarios and do not provide for practical action. Hence, one should distinguish them from applied solutions for calculating military-strategic balances and elaboration of arms control agreements. The latter depend on the current strategic landscape subject to constant, sometimes drastic change, as both the Cold War history and the recent developments testify. The choice of particular type of representation of strategic stability is determined by the nature of the most dangerous ongoing trends, and relies on a set of three basic groups of factors (political-military, military-technical, and military-strategic) existing at a given time. This necessitates constant revaluation of these factors and development of new practical measures to build up nuclear deterrence.The paper assesses the current set of relevant factors affecting stability of nuclear deterrence, and then compares it with the commonly used model of strategic stability based on the logic of arms control negotiations of the late 1980s. The author highlights the limitations of the latter model applicability to the present strategic landscape, and outlines the key factors that erode the current understanding of strategic stability (as it was stipulated in the 1990 U.S.–Soviet Joint Statement). In particular the author emphasizes the increasing complexity of international landscape as compared to the Cold War period: new and unanticipated challenges have affected all three above-mentioned groups of factors. The paper ends up with the analysis of the possible developments in the field of arms control that could alleviate tensions and increase strategic stability.

Robert Latiff is a retired US Air Force major general and a private consultant who provides advice on advanced technology matters to corporate and government clients and to universities. His current work includes research on the ethical implications of emerging and dual-use technologies. He has served on the staffs of Headquarters US Air Force and the Secretary of the Air Force. A member of the Bulletin of the Atomic Scientists' Science and Security Board, Latiff spoke recently with Bulletin editor-in-chief John Mecklin about the worsening international security situation as countries jockey for both military and private-sector advantage in space. This conversation occurred before Russia acknowledged testing an anti-satellite weapon in space, creating a debris field that could threaten the International Space Station and highlighting international tensions over use of space. [ABSTRACT FROM AUTHOR]

Russia, China, and the United States are in a race to develop and deploy hypersonic glide weapons. Hypersonic vehicles are defined as moving at a speed greater than five times the speed of sound. The US Defense Department has claimed these weapons will provide revolutionary new capabilities and will present daunting new threats against which there is currently no effective defense. Such claims have been repeated with little skepticism in the public and trade press. Many of the claims made for hypersonic weapons are, however, overstated and much of what they can do could be accomplished more easily and cheaply using better-established technology, typically via the modification of ballistic missile warheads. [ABSTRACT FROM AUTHOR]

The Nuclear Notebook is researched and written by Hans M. Kristensen, director of the Nuclear Information Project with the Federation of American Scientists, and Matt Korda, a research associate with the project. The Nuclear Notebook column has been published in the Bulletin of the Atomic Scientists since 1987. This issue examines the status of US missile defense, a key driver of the global nuclear arms race. According to the latest Missile Defense Review, the United States will continue to enhance its four primary missile defense systems – one for homeland defense and three for regional defense – without "any limitation or constraint." Doing so is likely to be destabilizing, as potential adversaries will attempt to build offensive systems to offset the United States' defensive systems. This dynamic is currently on display with Russia and China, both of which are developing missiles that are specifically designed to counter US missile defenses. [ABSTRACT FROM AUTHOR]

Nuclear weapons and global warming stand out as two principal threats to the survival of humanity. In each of these existential cases, two strategies born during the Cold War years are competing: abandon the respective systems, or defend against the consequences, once the harmful effects produced by those systems occur. The first approach to the nuclear and climate threat focuses on arms control, non-proliferation and disarmament and on greenhouse gas emission reductions and mitigation. The second approach involves active defense: in the nuclear realm, missile defenses against nuclear-armed delivery systems; for climate change, geoengineering that removes carbon dioxide from the atmosphere or changes the Earth's radiation balance. The more policies fail to reduce and constrain the underlying drivers of the nuclear and climate threats, the more measures to defend against the physical effects may seem justified. Ultimately, the overarching policy question centers on whether nuclear war and catastrophic climate change can be dealt with solely through reductions in the drivers of those threats, or if active defenses against them will be requested. [ABSTRACT FROM AUTHOR]

The United States and several other countries appear to be on a path toward the overt weaponization of space. The question is whether international law – specifically, amending the Outer Space Treaty – offers a way off that path and away from what some consider the inevitability of space warfare. This article addresses the challenges to amending the Outer Space Treaty as a way to slow down or abate what seems a fast-moving policy train, and offers suggestions regarding alternatives. [ABSTRACT FROM AUTHOR]

This paper discusses specific types of missile attacks the Democratic People’s Republic of Korea (DPRK) might launch in a conflict and identifies the key sources of uncertainty that US and allied political and military leaders must take into account in assessing how effective defense systems might be in stopping these attacks. A key finding is that while missile defenses might be able to blunt some kinds of attacks, the DPRK will have options for retaliatory missile attacks that can reach their targets despite the presence of defenses, and Pyongyang will know which options those are. The existence of this second set of cases is crucial for US and allied leaders to recognize if they are considering taking actions under the assumption that defenses will be effective in protecting US and allied populations.

Given the increasing tensions between world powers, missile defense is a topic that is more relevant than ever. However, information on the subject is often fragmented, confusing and untrustworthy. On the other hand, we believe that an informed overview of the current status is important for decision makers and citizens alike. A missile is essentially a guided rocket and therefore the term can be used to describe a very wide range of weapon systems. In this paper, we focus on long-range and intercontinental threats, which we believe are more important and problematic to defend against. We provide an overview of the two most common types of sensors, space-based infrared sensors and radars, and highlight their peculiarities and, most importantly, their drawbacks that severely limit their effectiveness. [ABSTRACT FROM AUTHOR]

Canada began to supply lethal weapons to Ukraine in February 2022 and sent heavy weapons two months later. In 2022 the Trudeau government agreed to increase the Canadian military contingent in Latvia as part of a plan to strengthen NATO's military presence in Eastern Europe. However, Canada did not comply with the NATO requirement for its members to spend 2% of GDP on defense. The aggravation of the Ukrainian crisis in 2022 did not lead to an increase in Canada's military commitments in Europe, but to an increase in the North American dimension in Canada's military policy. The Trudeau government used the aggravation of the Ukrainian crisis and hostilities in Europe to launch an expensive project with the United States to modernize their joint North American Aerospace Defense Command (NORAD). Canada's main contribution to the modernization of NORAD will be to provide territory for the new NORAD surveillance system, which will include over-the-horizon radars, a network of other radar systems in the Canadian North, and space-based surveillance. Providing its territory for the new NORAD surveillance system and the purchase of F-35 fighters means Canada's participation in the defense of North America from cruise and hypersonic missiles. There remains the possibility of Canadian support for US missile defense against ballistic missiles. Canada supports the admission of Finland and Sweden to NATO not just as new military allies in the Arctic, but also as countries like-minded with Canada. [ABSTRACT FROM AUTHOR]

The article considers possible options for conducting a hybrid war of the Russian Federation against Ukraine. The analysis of the existing basic concepts of dysfunction of the state system is carried out. Possible options for the influence of the Russian Federation to achieve a political goal in various areas (domains) are identified based on the concepts of strategic paralysis and operation based on effects The article analyses the main factors determining the operating environment conditions in which the Air Force of the Armed Forces of Ukraine will operate. There are analysed modern forces of air attack, means of air defence, tendencies of their development, application, and influence on the present and future operating environment. The threat of conducting combined information and strategic air operation as an effective tool for achieving the political goals of the Russian Federation in Ukraine is substantiated

The Russian vision of ballistic missile defense has reflected the specifics of the Russian/Soviet political system and decision-making mechanisms, and it is entangled with Moscow's peculiar perceptions of external military threats, nuclear deterrence, and conventional warfighting. In this article, the author attempts to answer three basic questions about that vision: What is Russia's long-term aim in regard to missile defense? Does it still want a new agreement with the United States that limits missile defense? And what kind of agreement could it be? [ABSTRACT FROM AUTHOR]

This article examines the relationship between US missile defense and the US-China security dilemma dynamics by developing the concept of diffuse signaling involving the Korean peninsula. We argue that the US' efforts to bolster deterrence against North Korea's growing threats through missile defense have resulted in China's countermeasures of enhancing survivability and penetrability of its second-strike capability, leading to downward spirals of tensions between Beijing and Washington. We explain how three structural factors – geography, the US alliance system, and nuclear asymmetry – have made diffuse signaling salient, thus making it very challenging for the United States to reassure China even when its actions targeted North Korea. The article empirically shows the action-reaction process through which China and the US have come to experience the aggravation of the security dilemma over the Korean peninsula. [ABSTRACT FROM AUTHOR]

Nukleare Fragen haben von jeher eine wichtige Rolle bei der Entwicklung der Beziehungen zwischen Moskau und Peking gespielt; sie waren und sind eine Quelle sowohl potentieller Konflikte als auch einer sich heute abzeichnenden Kooperation. Von 1964, als China seinen ersten Atomwaffentest durchführte, bis zur Ära Gorbatschow in den 1980er-Jahren waren die nuklearen Beziehungen zwischen der Sowjetunion und China erklärtermaßen von Gegnerschaft geprägt. Die Normalisierung der Beziehungen leitete eine Ära stillschweigend gegnerischer Beziehungen ein, die bis zur Ukraine-Krise dauerte. Während dieser Phase war es offensichtlich, dass Chinas wachsende militärische Macht Russland Sorgen bereitete und dass es daher entschlossen war, die nukleare Abschreckung gegenüber China aufrechtzuerhalten. Seit Beginn der Ukraine-Krise haben Russland und China eine immer engere Beziehung aufgebaut, die zu einer neuen Phase einer stillschweigenden nuklearen Kooperation mit koordinierten Bemühungen führte, die nukleare Abschreckung gegenüber den Vereinigten Staaten aufrechtzuerhalten. Beide Länder treten gemeinsam US-amerikanischen Anstrengungen entgegen, Raketenabwehrsysteme und hochpräzise konventionelle Waffen zu entwickeln. Sie stimmen ihre Positionen zu Fragen wie multilaterale Rüstungskontrolle und strategische Landschaft nach dem Ende des INF-Vertrags ab. Russland hilft China beim Bau eines Raketenfrühwarnsystems. Eine verstärkte Verteidigungskooperation eröffnet die Möglichkeit, Bestrebungen zur Aufrechterhaltung der nuklearen Abschreckung gegenüber den Vereinigten Staaten in einer Krise zu koordinieren. Nuclear issues have historically played an important role in the development of relations between Moscow and Beijing, acting as a source of both potential discord and emergent cooperation. From 1964, when China conducted its first nuclear test, until Soviet leader Mikhail Gorbachev's tenure in the 1980s, nuclear relations between the Soviet Union and China were explicitly adversarial. The normalization of relations introduced an era of implicitly adversarial relations that lasted until the Ukraine crisis. During this phase, Russia's concerns about China's growing military power and its resulting determination to maintain nuclear deterrence of China remained apparent. Since the onset of the Ukraine crisis, Russia and China have built an increasingly close relationship, leading to a new phase of implicitly cooperative nuclear relations featuring coordinated efforts to maintain nuclear deterrence of the United States. The two countries jointly oppose US efforts to build missile defense systems and high-precision conventional weapons. They coordinate their positions on such issues as multilateral arms control and the post-INF strategic landscape. Russia is helping China to build a missile attack early warning system. Growing levels of defense cooperation raise the possibility of coordinated efforts to maintain nuclear deterrence of the United States in a crisis. [ABSTRACT FROM AUTHOR]

During the latter part of the Cold War, many strategists thought of nuclear deterrence and arms control as two of the most essential stabilizing elements of the same strategy in managing an adversarial relationship. The renewed crisis between the West (the United States and NATO member states) and Russia demonstrates how critical these elements are to the strategic nuclear relationship. As a result of recent setbacks between Washington and Moscow in the past few years, arms control has taken a back seat, and the risk of conflict due to miscalculation is the highest it has been since the 1980s. If the United States and Russia want to rebuild trust and continue reducing the risk of nuclear use, a meaningful dialogue is needed to reconcile nuclear deterrence and nuclear arms control. How can the world’s two largest nuclear superpowers re-establish the harmony that once existed between deterrence and arms control? What should a stable framework look like for managing that nuclear relationship, taking into account other regional security challenges? The answer to these questions lies in establishing a new, common interpretation of US–Russian strategic stability. Both parties need to find mutually acceptable solutions to the challenges of reconciling nuclear deterrence and arms control. In general, the most important issues include disputes surrounding strategic and tactical nuclear weapons, global ballistic missile defense capabilities, and the problems of conventional precision-guided munitions. [ABSTRACT FROM PUBLISHER]

As long as the relationship between Russia and the West continues to be confrontational, the urgent task will be to stabilize and manage the confrontation. For NATO, this primarily means balancing deterrence and assurance measures to its easternmost allies without entering a new arms race. NATO should step up its efforts to foster talks with Russia on current military threats and on arms control, possibly by seeking reconstitution of the NATO-Russia Council as a crisis management forum and mechanism for dialog, dealing with dangerous military incidents and better communicating each side’s intentions. As for the Intermediate-range Nuclear Forces (INF) Treaty crisis and the interlinked issue of the European missile defense, US officials should consider face-saving options to reassure Russia that Western missile defense installations have no offensive capabilities – provided that Russia convinces the new US administration that it has returned to compliance with the INF Treaty. Over the mid- to long-term, NATO and Russia must initiate a serious and open dialogue about the two core issues at stake – the freedom and sovereignty of states to seek alliance membership and the (contradicting) Russian interest of maintaining a sphere of influence over its “near abroad.” A well-prepared conference – akin to the 1975 Helsinki Summit, with various preceding rounds of consultations at ambassadorial level, and including the nonaligned states in Europe – might be a way to kick-start the discussion. [ABSTRACT FROM PUBLISHER]

Over the last two administrations, protection of the homeland has formally been the top priority of US missile defense efforts. The importance of homeland or national missile defense is in the first instance a function of strategy – the refusal to accept a relationship based on mutual vulnerability with respect to certain kinds of threats. Understanding the history of homeland missile defense development is necessary to understand both the capabilities and shortfalls of the system fielded today. To be sure, there are simply too many missile-armed actors and too much uncertainty to accept complete vulnerability. But the interceptors fielded today also remain too limited, too modest, and insufficiently reliable relative to emerging threats. Significant improvements to interceptor reliability, capability, and capacity will therefore be needed to sustain and support the current strategy. [ABSTRACT FROM PUBLISHER]

Given the increasing tensions between world powers, missile defense is a topic that is more relevant than ever. However, information on the subject is often fragmented, confusing and untrustworthy. On the other hand, we believe that an informed overview of the current status is important for decision makers and citizens alike. A missile is essentially a guided rocket and therefore the term can be used to describe a very wide range of weapon systems. In this paper, we focus on long-range and intercontinental threats, which we believe are more important and problematic to defend against. We provide an overview of the two most common types of sensors, space-based infrared sensors and radars, and highlight their peculiarities and, most importantly, their drawbacks that severely limit their effectiveness.

Since 2002, when the United States withdrew from the Anti-Ballistic Missile Treaty, the international arms control regime has included no limits on missile defense. Washington wants to keep it that way, insisting that it “will continue to reject any negotiated restraints on US ballistic missile defenses.” Many experts believe that missile defense undermines strategic stability; but some argue that missile defense can play a role in denuclearization. Here, Wu Riqiang of China, Tatiana Anichkina of Russia (2015), and Oliver Thränert of Germany (2015) debate whether arms control arrangements should include limits on missile defense—or whether advances in missile defense should be encouraged because they might contribute to disarmament. [ABSTRACT FROM PUBLISHER]

Since 2002, when the United States withdrew from the Anti-Ballistic Missile Treaty, the international arms control regime has included no limits on missile defense. Washington wants to keep it that way, insisting that it “will continue to reject any negotiated restraints on US ballistic missile defenses.” Many experts believe that missile defense undermines strategic stability; but some argue that missile defense can play a role in denuclearization. Here, Wu Riqiang of China (2015), Tatiana Anichkina of Russia, and Oliver Thränert of Germany (2015) debate whether arms control arrangements should include limits on missile defense—or whether advances in missile defense should be encouraged because they might contribute to disarmament. [ABSTRACT FROM PUBLISHER]

Since 2002, when the United States withdrew from the Anti-Ballistic Missile Treaty, the international arms control regime has included no limits on missile defense. Washington wants to keep it that way, insisting that it “will continue to reject any negotiated restraints on US ballistic missile defenses.” Many experts believe that missile defense undermines strategic stability; but some argue that missile defense can play a role in denuclearization. Here, Wu Riqiang of China (2015), Tatiana Anichkina of Russia (2015), and Oliver Thränert of Germany debate whether arms control arrangements should include limits on missile defense—or whether advances in missile defense should be encouraged because they might contribute to disarmament. [ABSTRACT FROM PUBLISHER]

The United States and Russia have obligated themselves to pursuing complete nuclear disarmament. But despite the two countries’ treaty obligations, it’s reasonable to wonder if Russia and the United States will ever accept the constraints on power that total disarmament implies. Here, Wael Al Assad of Jordan (2015), Li Bin of China, and Sinan Ulgen of Turkey (2015) debate whether complete abolition of nuclear weapons is an appropriate goal for the disarmament movement—or whether disarmament might proceed faster if its aim were reducing stockpiles to the point that they represented only a minimum possible deterrent. [ABSTRACT FROM PUBLISHER]

A brief account is given of John O’Sullivan’s short but high-impact ca- reer. A link is provided to the video-recording of the ceremony at which he was posthumously granted the Pioneer Technology Award from the US Missile Defence Agency. The citations attest to his important technical and societal contributions. [ABSTRACT FROM AUTHOR]

In the face of deteriorating the regional security environment in East Asia, a noticeable growth of Japan’s defense capabilities and Tokyo’s departure from most self-restraints in the field of security policy look quite expected and natural process. At the same time, Japan continues to rely on the alliance with the United States. On the other hand, relations between Washington and Moscow are now at their lowest point since the Cold War. Japan itself has territorial claims to Russia. This means, based on confrontational logic that returns to the international agenda, that Japan’s traditionally reserved attitude towards Russia should be maintained. However, today we are witnessing a different situation. After the start of regular personal meetings between Russian President Vladimir Putin and Japanese Prime Minister Shinzo Abe, the dialogue is intensified on a wide range of issues, including those related to international security, and especially its regional aspect. Although certain background for that was noted before the Sochi meeting between V. Putin and S. Abe, this foreign policy turn, and, in particular, its speed, came as a surprise not only for Tokyo’s Western partners, but also for many Japanese politicians and experts. This article is devoted to the analysis of its possible causes, as well as the search for an answer to the next question.Is the dialogue between Russia and Japan a situational political maneuver or a step towards cooperation on security issues?

The Panel on Peace and Security of Northeast Asia (PSNA) was established in November 2016 in order to facilitate “political processes, through timely policy recommendations and public engagement, to create a NEA-NWFZ as part of establishing peace and security in the region” (PSNA Mission Statement. 20 November 2016. http://www.recna.nagasaki-u.ac.jp/recna/psna). The Panel consists of 17 members from 8 countries (Australia, China, Germany, Japan, Mongolia, the Republic of Korea, the UK and the US) with four co-chairs (Peter Hayes, Michael Hamel-Green, Chung-in Moon [acting co-chair, Yansoo Hwang] and Masao Tomonaga) (PSNA Members. http://www.recna.nagasaki-u.ac.jp/recna/psna-members). PSNA held its third meeting in Moscow, Russia, on 31 May–1 June 2018. This report contains two sections: (1) summary of the discussion at the third PSNA meeting and (2) comments from the co-chairs. While the contents of this report are based on the PSNA activities, the authors are responsible for the contents.

The view of both Moscow and Washington on ballistic missile defense (BMD) for a long time rested on the principle, formulated in the late 1960s, which held that anti-missile systems for defense of the territories were destabilizing, therefore limiting them would strengthen strategic stability. Since that time the USSR and then Russia always adhered to this principle, while the US at times rejected it (i.e. the SDI program of the 1980s) and by now has finally given it up altogether.Meanwhile , the majority of the independent leading experts assess the chances of the existing US missile defense to tangibly affect Russia’s nuclear strike capability as extremely low. However, the US unilateral withdrawal from the ABM Treaty in 2002 seriously undermined political trust between Moscow and Washington. The unwillingness of the US to provide Russia with a legally binding commitment not to direct its BMD system against it (including technical constraints) contributes to the problem. In addition, the US missile defense system is being built as an open-ended system with no future restrictions on its expansion and improvement.Russia has responded to the creation of the US national missile defense system with the modernization of its strategic nuclear forces and initiation of its own Air-Space Defense (ASD) system.The difference of the concepts of the BMD system development in the United States and the ASD system in Russia lies in that the US system is intended to defend against limited attacks of intercontinental ballistic missiles against the North American continent or of medium-range missiles against the US allies in Europe and the Pacific region. The Russian ASD is a multilayered system designed to protect against a protracted air-space of-fensive by the US/NATO involving high-precision conventional weapons (including future hypersonic and space-based systems) and limited use of nuclear weapons. Although there has been a long break in a meaning ful US-Russian dialogue on missile defense, it is still possible to reach some positive agreements. If the US and Russia resume negotiations on limitation and reduction of strategic offensive arms, it might open a window for a compromise on missile defense.Such a compromise can be based on an agreed threshold separating, on the one hand, missile defense systems that can significantly affect strategic stability by in-tercepting a large number of US or Russian ICBMs and SLBMs and, on the other hand – systems that will allow the US and Russia to protect their territories against at-tacks by third states or rogue regimes and would thus strengthen their mutual security. The first class of BMD systems would be subject to restrictions, while the second one would be given a green light. Moreover, in the second case there would reemerge an opportunity of the development of a joint defense systems of the two powers, which was declared in 2002 but never came true.

Literatures on the influences of missile defense (MD) on the existing nuclear deterrence are divided into negative and positive perspectives. However, both sides seem to make contradictory arguments. Skeptics argue that it is not feasible that MD influences deterrence stability but that it causes security dilemma and arms race, while proponents suggest that MD does not have to be perfect to reinforce deterrence stability but that it does not cause security dilemma and arms race. To fix this logical inconsistency, we identify an additional variable which is crucial in understanding the security dilemma mechanism in addition to Jervis's (1978) two variables. By adding another variable, a minimum MD effectiveness level required for deterrence success suggested by Quackenbush (2006), to Jervis's framework, we develop three hypotheses, two of which are novel on MD and its potential influences on deterrence stability and arms race. We then introduce a probabilistic model of the MD effectiveness by modifying Wilkening's (2000) and conduct simulation analysis to see if MD is more likely to incur security dilemma and arms race. Our simulation results show that MD influence is likely to be different depending on a potential challenger's national capability. Against a great power challenger, MD is least likely to meet the minimum MD effectiveness level required for deterrence success, so that the challenger is more likely to respond flexibly to the defender's buildup of MD. Against a newly nuclear-armed state, however, a defender's MD is more likely to satisfy the minimum MD effectiveness level, so that the defender is highly likely to respond flexibly to the potential challenger's reinforcement effort of its nuclear force. In either case, our simulation results indicate that arms races concerning MD among them are not likely to occur. [ABSTRACT FROM AUTHOR]

Turkish President Recep Tayyip Erdogan's blooming relationship with Russian President Vladimir Putin may signify a tipping point in the "East v. West" relationship that has been brewing since the dissolution of the Soviet Union in 1991. The recent developments between the two leaders could be seen as Turkey aligning itself with its neighbors to the East--a move that may prompt the formation of an "Eastern bloc" comprising states that have grown increasingly dissatisfied with the West. [ABSTRACT FROM AUTHOR]

One of the key areas of cooperation between URSS/Russia and US even during tense periods was strategic stability and treaties were signed in order, to have a security environment that was less prone to miscalculations or incidents that could lead to a nuclear war. The strategic stability between the two nuclear super-powers has deteriorated over time and now we have only one treaty that limits the number of strategic offensive arms between the parties that will expire in 2026. The article looks at ballistic missile defense systems as one of strategic stability component and questions its need for future arms control agreements. With both parties interested in a dialog on arms control it is likely that ballistic missile defense systems will be part of the negotiation process between Russia and US. Romania been a country that hosts such a NA TO system on its territory needs to pay attention to those discussions and to evaluate what options are most favorable to its security to communicate them to our strategic partners. [ABSTRACT FROM AUTHOR]

The contention over the quantity and quality of regional missile defenses forward-deployed by the United States in the Asia-Pacific region animates much of the US-China disagreement about strategic stability. The Chinese argue that the deployed assets exceed reasonable defensive requirements and suggest that if these missile-defense deployments continue, they will be forced to increase the size of their nuclear arsenal. In disagreement, the United States claims that regional missile defenses are defensive by design, limited in scope, and necessary to defeat a North Korean missile campaign. In this article, a series of simulation experiments were developed to empirically test these opposing arguments over missile defenses and strategic stability. The simulations indicate that current deployments are necessary for defense and proportional to the threat. The analysis also argues that current deployments do not possess the ability to alter the US-China strategic nuclear balance significantly. The article concludes with a discussion of other subjective aspects of national security that may explain Chinese concerns and explore possible ways to reassure China. [ABSTRACT FROM AUTHOR]

Multiple non-nuclear-armed states in alliances with nuclear-armed states are in the process of acquiring long-range, conventionally armed precision-strike weapons, some of which have potential to contribute to attacks on enemy nuclear forces. This change in the distribution of advanced military technologies has the unintended consequence of giving these non-nuclear-armed states an active role in strategic stability. We provide a theoretical framework for understanding the newly emerging pathways to nuclear use that result. We also investigate perceptions of the role of precision-strike capabilities in six non-nuclear-armed states at various stages in the process of developing these capabilities. [ABSTRACT FROM AUTHOR]

• This paper explores a three-dimensional tracking guidance strategy against high-maneuvering hypersonic vehicles. • The proposed guidance method utilizes a velocity control channel to increase tracking precision. • The wind field is accurately modeled to simulate the actual environment in the near-space to prevent impractical scenarios. • The backpropagation neural network extended state observer is proposed to estimate the uncertainty disturbance and design an adaptive control law to compensate for the tracking errors. • The proposed strategy combines fast nonsingular terminal sliding mode control and adaptive techniques to improve non-singularity, tracking accuracy, and estimation precision. This paper presents a three-dimensional disturbance observer-based adaptive tracking guidance scheme for the trajectory tracking problem of a missile intercepting a hypersonic vehicle with the wind field, autopilot lag dynamics, and input saturation. Unlike most of the existing missile trajectory tracking guidance systems without velocity controllability and external wind field model, the wind field model is added to the dynamic model, and the velocity control channel is introduced into the three-dimensional trajectory tracking guidance problem to prevent impractical scenarios and increase tracking precision. The proposed tracking guidance methodology incorporates the sliding mode and adaptive control techniques, in which the sliding mode motion is finite time stable independently of the tracking guidance system's initial conditions. Also, the super twisting switch control law is added to cope with the chattering problem. In this context, external uncertainty disturbances and unmeasured states are lumped into lump disturbance and estimated using the backpropagation neural network extended state observer. To this end, numerical simulations demonstrate the tracking to reach zero between 3 s and 5 s against various uncertainties in engineering practical, and position tracking errors are within 0.15 m, superior to the existing tracking guidance methods. [ABSTRACT FROM AUTHOR]