Those like Mr. Netanyahu who have opposed any agreement except on terms that cannot be realized should not engage in wishful thinking about the likelihood of such alternative approaches succeeding. They should be clear-eyed in comparing these alternatives with the kind of agreement that can be realized. Of course, if Iran is not prepared to accept a reasonable deal, the United States would have little choice but to turn to nondiplomatic approaches. But before it does, Washington should make every effort to negotiate a sound agreement which, while not eliminating Iran’s capability to produce nuclear weapons, can effectively deter Iran’s leaders from exercising that capability.