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"The purpose of sanctions is to bring the Iranian side to the negotiating table," said Li Baodong, China's U.N. ambassador, this week, explaining how Beijing could simultaneously support a new uranium-swap deal brokered by Brazil and Turkey and endorse new U.N. sanctions. The Obama Administration appears to have convinced China of its view that sanctions pressure is integral to achieving a diplomatic compromise. That two-track concept of combining punitive pressures with diplomatic engagement may also partly explain the U.S. slap-down of the deal brokered by Turkey and Brazil — even though that agreement may have been pursued at the encouragement of the Obama Administration.

Having likely been caught off guard by Iran's yes to a deal substantially similar to the...