US did not do any favor. It had left Iraq in a mess and without an air force, its policies in Syria had created the mess and its allies such as Saudis were at risk of becoming the next target of the zombies if Iraq had fallen. In all fairness, the air strikes were of a very limited benefit if at all. Just symbolic. The actual force was and is Iran. US can only create mess, which Iran then has to clean up. Such is the state of affairs. Some of the American mess:
* Created and supported taleban zombies and then went to war with them.
* Supported Saddam and then went to war with him.
* Created and supported Syrian rebels and now is fighting them.
* Made peace with Qaddafi when he gave up his nuke program and then killed him and Libya is now a nation run by a thousand war lords.
* Etc etc etc
We didn't leave Iraq a mess. The Iraqis kicked the U.S. out and thinking they can take on the terrorists themselves when they really can't. Wonder why? Look it up. Practically almost allowed all the weapons including tanks and artillery handed to the ISIS. Syria's policies left itself in a mess by shooting protesters and leaving many Syrian military members to join the FSA, even Syrian ambassadors quit in protest. And credit to the U.S. led coalition when Iraqi cities and towns were falling like dominoes, the airstrikes changed all that. Even the Iraqis admitted it and they were asking for that help.
We didn't create the Taliban, Pakistan did. 1994 remember? Saddam decided to invade Kuwait, we didn't tell him to do that. Qaddafi was killed by his own people. Consider all the things going on in the ME happened during what most people would call Arab Spring if you haven't noticed. Egypt, Syria, etc.