There's no doubt that America's Middle East policy has contributed mightily to the region's problems. But it's important to keep in mind that the real causes of regional chaos are local forces well beyond America's control — as this quote, from a Politico Magazine piece by former Obama administration official Philip Gordon, perfectly demonstrates:
In Iraq, the U.S. intervened and occupied, and the result was a costly disaster. In Libya, the U.S. intervened and did not occupy, and the result was a costly disaster. In Syria, the U.S. neither intervened nor occupied, and the result is a costly disaster.
Iraq is in the midst of a brutal fight against ISIS, Libya is split between two so-called governments and is increasingly a haven for jihadism, and Syria is stuck in a disastrous civil war. Though America used different amounts of force in all three places, Gordon correctly points out that none of the tactics prevented the country in question from descending into chaos.
That's because, Gordon argues, the fundamental causes of conflict in the region are local issues. Things like the Arab Spring and the subsequent collapse of governments in places like Syria and Yemen, the nasty regional competition between Saudi Arabia and Iran, and the failure of the Arab-Israeli peace process are fundamentally driven by the Middle East's internal issues, which America can't resolve.
"American leadership" — or the lack thereof — isn't the real problem. So while America's Middle East policy has certainly sometimes made the Middle East's conflicts worse — sometimes much worse — the region's real problems are its own.