Iran-China Relations: Past, Present, and Future The established discourse on the success or failure of the 2015 nuclear agreement (Joint Comprehensive Plan of Action) between Iran, on the one hand, and the 5+1 countries and EU, on the other, focuses predominantly on the dynamic of Iran-US relations. This might explain why the election of a fierce critic of the deal, Donald Trump, to the presidency of the United States led to much speculation about the death of the nuclear agreement. Even though there are good reasons for the supporters of JCPOA to worry about its fate, the survival of JCPOA depends also on Iran’s relations with other major players. This study focuses on relations with one such player, i.e. China. Since the conclusion of the agreement China and Iran have expanded not only their economic ties but their defense cooperation. In fact China has become the biggest exporter and importer market for Iran, as well as its major supplier of advanced weapons. But would China resist a reversal of this trend or even back off from supporting the JCPOA, if pressed by the US? China’s response has been an emphatic, no. But how reliable or durable this answer would be? Ever since the establishment of the Islamic Republic China’s relations with Iran, particularly at critical moments, have been influenced by the dynamic of its relations with the US. This tri-lateral character of Iran-China relations, therefore, creates uncertainty about whether China could resist US pressure and keep its promise to Iran. The first part of this paper focuses on the pre-JCPOA history of interactions between the two countries. The periods of Rafsanjani’s and Khatami’s administrations are particularly instructive in understanding the trilateral character of the relationship between Iran and China. As will be argued China’s distancing from Iran at some crucial moments, was to a good extent due to its interactions with the US. Would history repeats itself or is there hope for the breaking of this pattern? The rest of the paper is an attempt to provide an answer to this question by looking at several factors both specific and global, including Iran’s expanded ties with China, the latter’s increasing international power, and the impact of European and Russians’ view and behavior towards Iran’s and the JCPOA.