General Martin Dempsey, chairman of the Joint Chiefs of Staff, told CNN’s “Fareed Zakaria GPS” program that economic sanctions have to be given a chance to work.
“I think it would be premature to exclusively decide that the time for a military option was upon us,” Dempsey said.
“I think that the economic sanctions and the international cooperation that we’ve been able to gather around sanctions is beginning to have an effect,” he added.
Asked if Iranian leaders were acting rationally, Dempsey said: “We 
In recent weeks, there has been feverish media and Internet speculation that Israel or the United States might mount a preemptive strike at any moment. Both countries have denied any plans for any military action now.
Dempsey said he believed that “diplomacy is having an effect” on Iran. And he suggested that even if the West opted for a military solution, it had to be better prepared before it took such a step, indicating he did not feel the United States was prepared.
“I mean, fundamentally, we have to be prepared,” he said. “And that includes, for the most part, at this point, being prepared defensively.” He appeared to be referring to what US Defense Secretary Leon Panetta has cited several times as the likelihood that the Islamic Republic would retaliate against Americans for any attack.
Dempsey’s comments created a furor with many objections raised.
Michael Singh of the Washington Institute for Near East Policy cautioned, “It is important to understand what it means for a government to act rationally. It does not necessarily imply that the government sees the world the way we do or makes decisions we would make. Simply put,there are two essential criteria for rationality—first, the decisions are arrived at through a process of logical reasoning; second, that the decisions are the best ones given the choices available.”
Singh said the US intelligence community is in broad agreement that the Iranian government weighs costs and benefits and does not act on whim or claims of divine revelation.
But, he said, “We must also be aware that the regime likely lacks complete infomation or anything close to it. This is where the asumption that Iran acts rationally runs into the most trouble. Decisions in Iran are made by one man—Ali Kha-menehi. By all accounts, he has not traveled outside Iran since becoming Supreme Leader in 1989, is likely insulated by his aides from bad news or criticism, and depends on an increasingly narrow and homogenous power base that may not expose him to alternative opinions. One is unlikely to make a good decision if ill-informed or unaware of all the options. Nor can the regime make accurate judgments about US intentions if we do not clearly communicate our policies or red lines.”
Singh concluded, “Of course, even otherwise rational actors are prone to the occasional—and sometimes very consequential—irrational decision. And, in an authoritarian state with an aging and increasingly isolated leader, this risk goes up exponentially.”