Before the United States steps in another Middle East cow pie, there are questions that the American people deserve answers to.
First, what is the mission? This country can ill afford another military adventure run by politicians in Washington, D.C., with no idea of how to win a war. Since WWII ended, the U.S. has gone into Korea, Vietnam, Afghanistan, and Iraq twice. These were all undeclared "limited" wars, run by politicians and we didn't win any of them. Unless the U.S. is prepared for a full-scale invasion followed by long-term occupation, we should avoid involvement or risk doing more harm than good.
Secondly, who are we fighting? ISIS, the Sunnis? We helped Saddam Hussein, a Sunni, in the 1980s' Iran/Iraq war. Now that we deposed Saddam, Iraq's government is dominated by Shia Islam, just like Iran, our sworn enemy. The Sunnis and Shiites have been fighting for an eternity; no amount of U.S. intervention will change that.
How many times will the cycle of war repeat itself before we learn from our mistakes? In the words of Cicero, "It is the peculiar quality of a fool to perceive the faults of others and to forget his own."