Abstract. The article deals with the Agreement concluded in July of 2015 by the group of states “5+1” (the United States, Russia, Britain, France, China and Germany, and special envoy of the European Union) with Iran on its nuclear energy program (called Joint Comprehensive Plan of Action – JCPOA). It is argued, that despite some controversial points the Agreement as a whole is tangibly limiting, reducing and restructuring Iranian nuclear-technical assets, its development program, stockpile and quality of nuclear materials, and is prohibiting potentially military activities. Of special value is the broad and deep regime of transparency, safeguards and control by the International Atomic Energy Agency (IAEA), which goes much further than the existing safeguards associated with the Non-Proliferation Treaty (NPT). It is underlined that objectively (regardless of Iranian intentions) manufacturing of nuclear weapon or some secret military activity of significant scale is practically out of question in Iran during the term of various provisions of the Agreement (10–25 years). As proved by the article, a crucial factor in reaching the JCPOA were the U.S. and European Union economic and financial sanctions, adopted against Iran in 2012. They led to the profound economic crisis, which brought the change of government at presidential elections of 2013, and eventually facilitated Iranian concessions (foremost, on the scale of uranium enrichment, deep underground enrichment complex, plutonium-producing reactor, and the scale of transparency). On the other hand, in contrast to American and Russian official statements, the unprecedented tensions between Russia and the West around the Ukrainian crisis since the early 2014 seriously weakened the unity and diplomatic dominance of the “5+1” group of states. Hence, it turned impossible to achieve still more far-reaching agreements on some principle issues (in particular, on the necessity for Iran to receive the approval of the “5+1” and IAEA for the parameters of its nuclear energy program justifiable by peaceful needs – as suggested by the Interim Agreement of November 2013). This has created a precedent for other states to claim the right for developing nuclear energy programs with dual purpose or suspicious elements without obligatory and plausible peaceful justification. It is also underlined, that the future impact of the Agreement on the global system and regimes of nuclear non-proliferation is unclear. The positive side is the JCPOA role in preventing the new war in the Gulf. The dubious aspect is that universalization of the limitations and transparency norms of the Agreement for the purpose of the Non-Proliferation Treaty enhancement is rejected by a number of states, foremost by Russia. It keeps to a tough position that the Agreement is exceptionally Iranian case, which is not applicable to other states, and in fact this point is legally fixed in JCPOA and IAEA documents. This Russian position is in line with its general stance against more restrictive interpretation of the NPT norms and against more intrusive IAEA safeguards. No doubt, in the foreseeable future, these issues will be a matter of serious controversies among states regarding the enhancement of the NPT and overall non-proliferation system and regimes.