The Islamic State is much more of a problem for its neighbors than it is for the US. Chiefly for Syria and Iraq, which are under direct attack, but also for Russia and Iran -- Russia because its largest foreign naval base is in Syria (now that Crimea is not foreign), and Iran because it's closely allied with Iraq as the two big Shia countries. And that may not seem like such a bad thing to US leadership, since Russia and Iran are the two main leaders of the assault on the dollar as international reserve currency, now that Saddam and Gaddafi are dead.

There's a history of using the Sunni Arabs of the Fertile Crescent to keep rebels in line. They invaded Iran after the great setback and humiliation when the US-backed Shah was overthrown and the US embassy was occupied. Then they invaded Kuwait when the big US banks were all on the verge of collapse and the Kuwaiti royal family thought they didn't need US protection and moved their deposits to German and Japanese banks. Everyone knows the story of the US ambassador giving them the go-ahead to invade Kuwait, but most people assume that was just a mistake, a part of the Keystone Kops theory of US foreign policy.