Jonathan Tobin rightly dismisses as dangerous any Israeli attempt to play China or Russia off the United States out of frustration with the Iran policy of the Obama administration. When it comes to dealing with the immediate threat posed by Iran, only Washington has superpower leverage, and if Israel wanders off the reservation, it will only damage itself.

But Jonathan makes a further claim: “Israel’s long-term safety must be seen as linked to the ability of the United States to maintain its status as the leader of the free world. Even at times of great tension with Washington, Israelis must never forget that it is not just that they have no viable alternatives to the U.S. but that American power remains the best hope of freedom for all nations.” This “linkage” is problematic, and its acceptance could blind Israelis to what they need to do to survive through the next half-century.

The problem with American power, like all power, is that it waxes and wanes. We have become used to the notion that U.S. preeminence in the world and the Middle East is a constant. But it isn’t so. Geography has rendered the United States the most self-contained superpower in history. As a result, it goes through manic bouts of interventionism and isolationism, and sometimes awakens to the responsibilities of its power too late. It did so during the Holocaust, and it did so during the first years of Israeli independence, when the fledgling Jewish state had to look to the Soviet Union and France for the arms essential to its defense. The simple truth is that Israel cannot rely on the United States to do just the right thing at just the right time. That’s at the heart of the crisis of confidence between the United States and Israel over Iran, and its sources run deeper than the particular world view of Barack Obama....