It’s unfortunate but inevitable that momentous international events — like the current Iranian revolution, as we must now call it — get used as fodder for domestic political controversy. That’s especially true in the United States, whose superpower status has led its political class to think of everything that happens in the world as their concern or responsibility.

Hence the intensity of the debate over Barack Obama’s response to events in Iran. (Andrew Sullivan’s blog is about the best place to follow this debate.) While there is a consensus of support for the rebels right across the political spectrum — only a few extremists of left and right are in Ahmadinejad’s camp — there is disagreement over how to respond. Neoconservatives have attacked Obama for being too restrained, with the most unhinged of them suggesting that he secretly favours Ahmadinejad.

The key point here, which it doesn’t take much foreign policy expertise to work out, is that America’s leverage in Iran is very small. Being seen as the US-supported candidate in Iran is not a winning strategy. Obama’s comments so far show an acute recognition of that fact: explicit support for the rebels risks being counter-productive.

It’s more effective to offer support behind the scenes, as with the US government’s moves earlier this week to keep the Twitter network open at a crucial time. As one liberal blogger put it, “It’s almost as if they’re more concerned with what actually contributes to human rights in Iran than with what provides the best fap-fodder for hawks at home. Crazy.”

But restraint is also very much Obama’s normal mode of operation. In Matt Steinglass’s words, “He’s always a step or two behind where his supporters want him to be, getting pulled along by their enthusiasm, rather than out ahead of them where he might get cut off.”

So far this incredible self-control has been extremely successful. But it has its limits: just this week, polling showed that Obama’s approval ratings remain high while support for many of his policies, including economic strategy and plans for health care reform does not. As The New York Times put it, “his political strength still rests on faith in his leadership rather than concrete results.”

Another way of looking at that is to observe that the Republican leadership is so incompetent that, despite being on the same side as public opinion on key domestic issues, they have been unable to translate that into any higher standing for themselves or any reduction in Obama’s popularity.

Sure enough, Republican incompetence has been on show over Iran as well.

John McCain, whose credibility is probably not helped by memories of him singing “Bomb, bomb Iran” in 2007 during his presidential campaign, is only the most prominent to be calling for confrontation regardless of consequences.

Maybe Obama should be doing more, but he can hardly be blamed for having a vivid sense of what trouble following the neocons has led to in the past.