Jeffrey Goldberg writes today: “President Obama promised to kill Osama Bin Laden. He did. He promised to withdraw American troops from Iraq. He did. He promised to kill Anwar al-Awlaki. He did. He promised to make Afghanistan the focus of the War on Terror. He did. Obama has said, repeatedly, publicly and unconditionally, that a nuclear-armed Iran is unacceptable to him. He has said that all options are on the table. If I were the Iranians, I would take him at his word. And if I were Israel, I would take him at his word as well. (Obama’s feelings about Prime Minister Netanyahu are not particularly material in this discussion, in part because the president understands that Iran is a problem for the world, not just for Israel.)”

The question of whether Israel should trust Obama is intriguing on two levels: 1) Will Obama use force to prevent Iran from getting a nuclear weapon and 2) Should Israel entrust its existence to Obama?

Goldberg is correct in stating: “First, Iran and the U.S. have been waging a three-decade war for domination of the Middle East. If Iran goes nuclear, it will have won this war. American power in the Middle East will have been eclipsed, and Obama will look toothless.” I couldn’t agree more. Even from a purely personal standpoint Obama should recognize he cannot allow this to occur. Jonathan Schanzer of the Foundation for Defense of Democracies put it this way to me: “Obama is deeply concerned about his own legacy. He does not want to be remembered as the US president who let Iran go nuclear. It should also be noted that presidents can get a significant boost in popularity during period of conflict (as long as they don’t drag on for years, as we have recently observed).”

Goldberg continues: “Second, every U.S. ally in the Middle East — Israel, the Gulf countries and Turkey, especially — fears a nuclear Iran. The president would have their complete support.” Complete? I’m not so sure about that. Given how little sticking power the U.S. has shown, it’s certainly possible the support would be spotty, as powers hedge their bets.

Goldberg’s least effective argument is this: “Finally, the president has a deep understanding of Jewish history, and is repulsed by Iranian anti-Semitism. He doesn’t want to be remembered as the president who failed to guarantee Israel’s existence.” Let’s not get carried away with Obama’s command of Jewish history or his willingness to rationalize that not taking action is “good for Israel,” just as his sometimes-hostile public stance toward the Jewish state really is in everyone’s best interests.

However you assess Goldberg’s arguments, they don’t answer the question of whether Obama will take military action against Iran or will he dither — that is, insist on elusive international action or rationalize a containment strategy that would be “less disruptive,” as he advisers have told us. It’s not simply a matter of policy preference. It’s a matter of courage and will. If he takes military action, Obama would be starting a war, one with uncertain ramifications and theoretically requiring prolonged commitment by the United States. Given that choice and a half-baked theory of containment, which way would Obama come out? Goldberg is confident he knows the answer; I’m not confident Obama knows the answer.

That brings us to the second question: Should Israel entrust its survival to the U.S. president? Well, at some level the issue will come to a discussion: The U.S. or Israel? Who’s going to take action now against Iran or let it go nuclear later? And when is the point of no return. Perhaps there will be an agreement. But frankly, no Israeli prime minister should or could tolerate the same level of risk that an American president might be willing to bear. If there’s a 10 percent chance it is now or never, could an Israeli prime minister hold off?

Ultimately, the best guarantee of U.S. action is the knowledge that Israel, if forced to act alone, will do so. Then the question for Obama becomes: “Who can best do this?,” not “Should we put our eggs in the containment basket?” Let’s hope Goldberg is right. But if he’s not, Israel won’t be caught flat-footed. I am certain.