The Trump administration reacted to the apparent use of chemical weapons against civilians by the Bashar al-Assad government with a flurry of air strikes against a Syrian military airfield Thursday night.

The bombing occurred after a widespread clamor for Trump to “do something” and without a thorough debate about what ultimate goal the U.S. is attempting to reach.

This is exactly what Trump’s defense secretary, Jim Mattis, warned about in remarks he made in 2013.

Mattis had just retired from his role as the commander of U.S. Central Command, and agreed to be interviewed by CNN’s Wolf Blitzer about U.S. policy in the Middle East.

When Blitzer asked Mattis about his views on military intervention against Syria’s government, the former general sounded a stern note of caution. He stressed that the United States should not intervene without a serious and well thought-out plan, and that it would be an enormous commitment.

“On Syria, ladies and gentlemen, we are going to have to determine what is the end state we want. This war needs to be ended as rapidly as possible. That’s the bottom line,” Mattis began. “But if the Americans go in, if the Americans take leadership, if the Americans take ownership of this, it’s going to be a full-throated, very, very serious war. And anyone who says this is going to be easy, that we can do a no-fly zone and it’ll be cheap, I would discount that on the outset.”

He then drew an analogy to the war in Iraq.

“We need to be very clear about our military end state, contributing to what political end state,” said Mattis. “Otherwise, you’re liable to invade a country, pull down a statue, and then say, ‘Now what do we do?'” Hearing this, the audience burst into laughter.

“We’ve been there,” Blitzer admitted.