In 2003, then-war-supporter Andrew Sullivan wrote:

One of the many layers of the arguments for invading Iraq focused on the difficulties of waging a serious war on terror from a distant remove. Being based in Iraq helpsus notonly because of actual bases; but because the American presence there diverts terrorist attention away from elsewhere. By confronting them directly in Iraq, we get to engage them in a military setting that plays to our strengths rather than to theirs’. Continued conflict in Iraq, in other words, needn’t always be bad news. It may be a sign that we are drawing the terrorists out of the woodwork and tackling them in the open.

This was the essence of the so-called "flypaper theory" — the notion being that if the U.S. had presence in Iraq, all the "bad guys" would flock to Iraq to fight us, and we could fight them there — out in the open.  That way, we wouldn’t have to run all around the world fighting the evil-doers.

Turns out, that’s not happening at all.  In fact, the opposite is happening.  There is an outward flow of jihadists from Iraq into neighboring countries, like Lebanon and Jordan.  The New York Times explains:

The Iraq war, which for years has drawn militants from around the world, is beginning to export fighters and the tactics they have honed in the insurgency to neighboring countries and beyond, according to American, European and Middle Eastern government officials and interviews with militant leaders in Lebanon, Jordan and London.

Some of the fighters appear to be leaving as part of the waves of Iraqi refugees crossing borders that government officials acknowledge they struggle to control. But others are dispatched from Iraq for specific missions. In the Jordanian airport plot, the authorities said they believed that the bomb maker flew from Baghdad to prepare the explosives for Mr. Darsi.

Estimating the number of fighters leaving Iraq is at least as difficult as it has been to count foreign militants joining the insurgency. But early signs of an exodus are clear, and officials in the United States and the Middle East say the potential for veterans of the insurgency to spread far beyond Iraq is significant.