The problems with the Iranian-Afghan water issue are the result of the demarcation of the border between the two countries caused by external interference at different historical periods. Over the past 150 years, four agreements have been signed between Iran and Afghanistan on the use of water from border rivers, but they have never been fully implemented. The issue of water resources is a very sensitive for Iran and Afghanistan. Over the years, the emergence of complex environmental, agricultural, economic, social, legal, security, political and military factors has exacerbated the situation. Out of geopolitical interests, Great Britain and Russia divided the territories of Iran and Afghanistan into zones of influence in 1907, essentially depriving these countries of their sovereignty. In this situation, the settlement of border disputes between Iran and Afghanistan was entrusted to a third party, namely Great Britain, Turkey and the United States. Since the aforementioned countries were guided by their own interests when drawing the border between Iran and Afghanistan, as a result of the demarcation between the sides, it was not possible to find a solution to the water use of the Helmand River that would satisfy both Iran and Afghanistan. Iran and Afghanistan, as sovereign states, first began direct talks to resolve the water issue at the beginning of the 1970s. In 1973, the first and the only contract still in force was signed. In order to fully resolve the water issue between Iran and Afghanistan, it is essential to create an atmosphere of mutual trust between the two sides. The security, socio-economic and environmental factors that have emerged over the last two decades have hindered the formation of such an atmosphere. Attempts by the Iranian and Afghan authorities to find a comprehensive solution to the problem after the Islamic Revolution have failed. The water issue is now so complicated that it can only be resolved through political will. However, since both sides cannot but consider the socio-economic situation of the population and social pressures when making a political decision, they will be more inclined to make populist decisions in order to avoid aggravation of the internal situation. The hydropolitical policy directions pursued by Iran and Afghanistan indicate that the sides will also continue to use the water factor as a tool of pressure in the near future. Evaluating the statements of the Iranian military-political management on the water issue, it can be stated that the water issue has long ceased to be a merely ecological and agricultural one. Given the ethno-religious picture of the Sistan-Baluchestan province of Iran and the challenges threatening the province (terrorism, separatism), Iranian security forces are extremely sensitive to the water issue. Afghanistan is a strategically significant neighbor for Iran. The water issue is the possible factor that puts Iran in a serious dilemma. On the one hand, Tehran cannot jeopardize bilateral relations due to socio-economic problems in Sistan-Baluchestan, but on the other hand, failure to resolve the water issue can exacerbate the already tense situation in the province, leading to border clashes, which, in turn, could escalate into a large-scale conflict. Regular armed clashes on the Iranian-Afghan border since the formation of the Taliban interim government in Afghanistan, as well as the fact that Afghanistan’s neighboring countries have not formally recognized the Taliban authorities, make it almost impossible to reach definite agreements. Iran, despite tough public statements, will continue to pursue a cautious policy towards the Taliban in its real politics. If it puts pressure on the Taliban over water issue, the Taliban will simply block the flow of the Hirmand River into Iran, as they did in the 1990s. In that case, Iran will have to resort to tough measures to solve the problem, which, however, is not in Iran’s strategic interests. The fact that Iran considers the matter of reviewing the contract of 1973 while taking into account the needs of the people of the Hirmand River Basin is unrealistic and it will never be acceptable for Afghanistan. The demand for water on both sides will increase. The Hirmand River is not physically able to meet the demand of both sides. Mutual pressure can only ensure short-term solutions. Consequently, the water issue can be resolved comprehensively only through reciprocal concessions (Iran can either pay for uninterrupted, regulated water supply with oil or not charge transit money from Afghanistan) and by signing a new agreement based on this compromise.