U.S. President Barack Obama has decided to abandon plans to deploy a missile defense system in Europe to counter an Iranian missile threat. The way it was carried out raises questions about U.S. commitments to its allies. The missile defense program is a partnership between Washington and its allies. As such, decisions regarding its future should be made together, not imposed by one on another.

Still, Mr. Obama's decision makes sense. It has removed the probably greatest barrier to the progress of negotiations between the United States and Russia for nuclear arms reductions. It is strongly hoped that the U.S. and Russia will make a great step forward to conclude their negotiations by yearend.

Concerned about the prospect of Iranian missiles attacking the U.S. and its European allies, former U.S. President George W. Bush developed a plan that would deploy a sophisticated radar system in the Czech Republic and 10 ground-based interceptors in Poland. That decision infuriated Russia, which insisted that the deployment threatened to neutralize its nuclear deterrent, a charge that the U.S. consistently denied. Equally important for Moscow but rarely stated outright was fear that the integration of the two countries more deeply into the U.S. defense system would undercut Russian influence in an area that it considers part of its sphere of influence.