A new day is dawning in Sino-Iranian relations. Earlier this month, Iranian officials revealed publiclythat they were in the final stages of negotiations with China on a sprawling, 25-year strategic pact. The deal will, if implemented in full, dramatically expand military, economic, and political ties between the two countries. The new accord should not be surprising; Tehran and Beijing have historically cooperated on everything from arms sales to energy. Even so, the agreement – which is scheduled to be finalized in coming weeks – represents a landmark expansion of bilateral relations between the two strategic partners. It is also a development with major implications for regional geopolitics and a clear threat to the United States’ efforts to isolate and contain the Islamic Republic.