Robert Kagan, veteran warmonger extraordinaire, wants to know what the “utility” would be of admitting that the war on Iraq was “a mistake.” I’m glad he asked. But, “mistake” is not exactly the word.

The U.S. has signaled to the world that it is an unreliable partner, ushering in an era of global instability where the Middle East is now “up for grabs,” according to Robert Kagan, a senior fellow at ...