Having suffered years of diplomatic and economic isolation due to international sanctions, Iran has gradually deepened its relationship with China, which has stepped in to become a critical strategic partner for Iran. Economically, China is Iran’s top trading partner, a leading energy importer, and a top investor. The two countries also have longstanding military ties, consisting of strong cooperation in the 1980s and 1990s and more modest cooperation today, with semiregular engagements such as high-level military exchanges, exercises, and port calls. Beijing and Tehran’s March 2021 25-year cooperation agreement reflects their deepening relationship, which continues to grow as the two countries strengthen their coordination on issues of mutual interest.
Despite their enduring strategic partnership, Beijing has carefully calibrated the growth of bilateral ties in an attempt to balance its other interests in the region. While Tehran has touted the new 25-year cooperation agreement as a milestone in Sino-Iranian relations, Beijing has downplayed its significance. Although Beijing does not seek to completely subvert the stability provided by the United States in the Middle East, increased Sino-Iranian coordination undermines the effectiveness of important U.S. policies such as nuclear sanctions. Meanwhile, Beijing’s tacit approval of proliferation activities supporting Iran’s missile program puts U.S. troops in the region at continued risk.