Iraq A Terrorist "University?"

With U.S. forces putting the pressure on al Qaeda strongholds and the military admitting top leaders have escaped, intelligence agencies have come to an ominous conclusion: al Qaeda fighters who slip away are ready to expand their fight to Europe and the gulf.

A letter from al Qaeda's No. 2, intercepted last month, urged foreign fighters to take their campaign of terror beyond Iraq's borders, CBS News correspondent Sheila MacVicar reports exclusively.

The jihadi veterans of Iraq are battled-hardened survivors of the world's toughest urban guerilla fighting — against some of the worlds' best soldiers.

"If you survive that, you are able to do anything essentially," said Thomas Sanderson, Center for Stratigic and International Studies.

Sanderson, an expert in global terror threats, is preparing to publish a year-long study tracking foreign fighters.

"You have that impact that says I survived that all those groups that were arrayed against me and that gives you a sense of infallibility and lethality," Sanderson said.

In an audiotape posted on the Internet, one insurgent leader describes it this way: If Afghanistan was a school of terror, says Abu Omar al Baghdadi, Iraq is a university of terrorism.

"They've been able to learn how to miniaturize bombs, how to surveil, how to countersurveil, how to snipe, how to escape," Sanderson said. "How to use safe houses, how to disguise themselves, how to lay low in the midst of an occupying force."

And how to move around the region with ease. Intelligence sources tell CBS News that under pressure from the United States, the route in through Syria is now largely closed, in some cases jihadists are using European airports with direct flights to northern Iraq.

The trip out now takes survivors to neighboring Arab states, North Africa and Europe.

And the impact is spreading.

In Lebanon, al Qaeda veterans from Iraq held off U.S.-equipped Lebanese special forces for a month.

In Algeria, a bombing campaign carried out by local Islamists allied with al Qaeda used techniques imported from Iraq. Intelligence agencies call Algeria the 'gateway' to Europe.

And across Europe, police have broken up networks used to recruit and send would-be fighters to Iraq. That hasn't stemmed the flow.

French intelligence acknowledges tracking about 30 people they know have left France for Iraq. A dozen are dead, a dozen more in custody. The rest have vanished, and the French admit they do not know where they are.

But they do know they're part of a new generation of terrorists, in the words of one analyst "rock stars" to their followers trained in war, committed to destruction and some of them may be headed our way.