AP Photo

There were two major nuclear non-proliferation conferences in April, one in Washington and one in Tehran. China attended both.

The Barack Obama administration was highly gratified that Chinese President Hu Jintao attended the Nuclear Security Summit in Washington. But China also sent an assistant foreign minister to the Tehran International Conference on Disarmament and Non-Proliferation, where he pleased his hosts by reiterating a call for continued negotiation and diplomacy to resolve the Iran nuclear crisis.

After months of...