The trilateral coordination among China, EU and the US within the framework of the P5+1 mechanism is a major part of the global effort to deal with the Iranian nuclear issue. China’s active participation in the process is one of many recent two-way interactions between China and the west, and exemplifies China’s gradual integration into the international community.

In 2003, shortly after the invasion of Iraq overthrew the Saddam regime, the “EU troika” of Britain, France and Germany launched a diplomatic effort to find a peaceful solution to the Iranian nuclear issue. The intention was to find an alternative to unilateral military action by the U.S. The EU initiative was partly an embodiment of its concept of normative diplomacy, and partly intended to avoid another awkward US-EU split like the one on the eve of the Iraq war. Eventually, considering, as Henry Kissinger argued, that “on a matter so directly involving its security, the United States should not negotiate through proxies, however closely allied,” the U.S. joined the EU initiative.

China was drawn into the P5+1 mechanism (the EU troika plus the U.S., Russia and China) in early 2006, when the U.S. and EU were considering how to respond to Iran’s restarting some nuclear activities after the election of Ahmadinejad as President in 2005. The inclusion of China reflected US and EU concerns that Iran might play off the nuclear powers against each other. The west was concerned that Beijing's economic interests might lead it to dilute international pressure on Tehran. From a broader perspective, the West’s invitation to China to take part in the discussions was a recognition of China’s growing weight in international affairs.

China’s willingness to get involved can be attributed to two factors: Firstly China has economic interests in Iran, and therefore has a stake in seeing a peaceful resolution of the issue; secondly, China like any other major power considers nuclear proliferation against its national interests, not to mention that proliferation would further complicate the situation in a region that is so crucial to maintaining stable energy supplies. Debate around China’s international responsibility as an emerging global power coincided with the move.

The troika and the six-party talks were initially effective. In 2003, Iran signed an additional protocol of the non-proliferation treaty allowing IAEA inspections; in 2004, Iran and the troika signed the Paris agreement, under which Iran suspended its nuclear activity. The six party talks also promoted consensus among the P5+1, including maintaining the authority of the non-proliferation regime, and emphasizing the importance of negotiations as the way to address the issue.