PHILADELPHIA (CBS) — Chris Stigall spoke with former Lieutenant Colonel and the current Headmaster at the Havertown School, John Nagl, about a piece he’s written calling for more engagement in the fight against ISIL in Syria and Iraq.

Nagl said President Obama made a mistake by not insisting that military advisors remain in Iraq following the troop withdrawal in 2011.

“This was a case where the President of the United States made a decision against the advice of his military advisors. I think that there is a lot of evidence to suggest that was a very bad decision. I think he has de facto admitted it was a bad decision by sending, now, more advisors back to Iraq.”

He stated that the tactics used by ISIL and other terrorists groups make defeating them a much more difficult task.

“Certainly it would be convenient if we could arrange for total domination of our enemies. Unfortunately, it’s much harder to achieve now than it used to be. My first war was Operation Desert Storm…That was a war where our enemies fought us conventionally, tank on tank. We could destroy them utterly. The world watched that war. They paid attention. They realized if you tried to take the United States conventionally, we’re going to destroy you. So they’ve now started fighting us as insurgents and terrorists where they hide among the sea of the people, they’re fish swimming in the sea of the people, to use Mao’s phrase. It’s a much harder kind of war for us to win.”

Nagl believes that immediate action is necessary to prevent the crisis posed by ISIL from spiraling out of control.

“If there has been a core tenant of American foreign policy since the attacks of September 11, it has been never again give terror groups, international terror groups, ground from which they can plan and execute attacks on the United States and our friends and allies around the globe…We have now yielded to a group that is so violent, it was thrown out by Al-Qaeda…The entire Middle East could go. We could see full Sunni-Shia civil war. This is really, really bad.”