"When you start doing things that would be better with the Security Council's endorsement, does it show weakness or strength?" said George Perkovich, the director of the nonproliferation program at the Carnegie Endowment for International Peace. "Iran could argue that 'the U.S. couldn't even get the Security Council backing, and so we are winning.'"
"There is a general reluctance to follow the U.S. lead," he said. "Our negotiating power is diminished, which is regrettable."