Part of this is domestic politics. Mitt Romney was probably making a smart political move to jump on Obama's hot mic comments to Russian President Dmitri Medvedev about how the U.S. couldn't make another nuclear arms reduction deal until after the election. Reducing American might is politically unpopular (even though we don't actually need those thousands of nuclear warheads) as is the idea of offering concessions to another, not-so-friendly country. It would be bad politics for Obama to enter tough and maybe even painful negotiations with a competing nation, probably because this conflicts with the Reagan-era idea that America's inherent strength and goodness means that we dictate terms to the world. But even Reagan compromised and horse-traded with Moscow, though he also had the good sense not to do it during an election.

This is the big conflict between how U.S. leaders negotiate American politics and American foreign policy: the former requires confidence, the latter humility. But the two are not inseparable. Maybe because our political system promotes leaders who believe most strongly in American power, or maybe because it pressures those leaders to exercise more power than they might actually have, it can often seem that the U.S. is constantly falling short of our ambitions. We can't stop Israeli settlement growth, Iranian nuclear development, Sudanese civil war, AIDS in Africa, or terrorism in Pakistan, even though Americans presidents keep insisting that we will.

There was a time when we seemed to have more influence on how other countries behaved. In this 1980 map of Cold War alliances, the "blue" countries would reliably, if not always, follow U.S. leadership. Part of that was because we had easier requests then; it's one thing to tell Pakistani generals to train anti-Soviet fighters, quite another to ask them to give up power to democratic institutions. But the threat of Soviet domination gave us a common mission that made cooperation more attractive and American leadership more desirable. There's no more great red menace to unify the majority of the world under American leadership. Other countries don't need us in the way that they used to.

The good news is that American and global interests still tend to line up pretty frequently. That's not a coincidence. The U.S. does more than any other country at maintaining global peace, cooperation, and free trade. The rest of the world might not depend on American protection from the Soviet Union, but it depends on the U.S.-enforced political and economic order. That's the new American leadership. When China slashed its Iranian oil imports by half -- a big blow to Tehran and a boost to the U.S.-led effort to isolate Iran -- it wasn't because Obama called up Chinese President Hu Jintao and told him to do it. The U.S., through a lot of difficult and sometimes painful diplomatic and economic maneuvering, found a way to line up American and Chinese interests.