Another way of thinking about this is that Americans don’t like it when the bad guys are kicking the U.S. around on the world stage and the president doesn’t seem to have any sort of plan to do anything about it. But that doesn’t necessarily mean that, in actuality, they are willing to do whatever it takes to stop the bad guys.

Even at the most hawkish moment in modern U.S. history, in the aftermath of the Sept. 11 attacks, there were limits to the sacrifices that Americans were willing to make.

President Bush anticipated this in his speech to a joint session of Congress following the attacks. He told the members of the military to be ready, but advised Americans to go back to their lives and keep the economy thriving. There was never a broader effort to mobilize the home front. And when he invaded Iraq and attempted to build a democracy there, he did so with a relatively small number of troops intending to leave a light footprint.

In time, Americans turned on the war and elected Obama on a pledge to end the conflict.