PENJWIN, Iraq, Sept. 15 — Through the dusty mountains along the northeastern border with Iran, Islamist fighters intent on attacking U.S. troops are finding their way into Iraq.

     They come from Saudi Arabia, Qatar, Kuwait, Afghanistan and other countries, crossing the frontier along well-known smuggling routes.

     The Iraqi Kurds who are in charge of this region say they are capturing as many of these fighters as they can. In exclusive interviews held in a Sulaymaniyah prison with guards looking on, some of the fighters told ABCNEWS how America's plans to attack Iraq drew them here — and how the U.S. presence keeps them here.

     Sangar Aref Saeed is a compact, 26-year-old shepherd from northeastern Iraq who last year joined the military wing of Ansar al-Islam, a group the prisoners say is closely allied with al Qaeda. He fled to Iran when the war began. Iranian security officials, he said, allowed him and other fighters to regroup there.

     In a large meeting, the fighters were addressed by a man Saeed believed was from al Qaeda. "He said we should act so the world knows we still exist," Saeed told ABCNEWS, speaking in Kurdish. "He said we could not refuse any mission, whether in northern or southern Iraq, whatever the instructions."

     Other fighters stayed in Iraq and fought. "We were told to attack Americans wherever they are, any way possible," said a 25-year-old chemistry student who asked not to be named.

Weak Borders Mean More Attacks

     The prisoners described a network of contacts throughout Iraq that they said is still in operation. The contacts provided money and shelter as they sought the opportunity to attack U.S. troops, the prisoners said.

     "They go wherever security is weak — Najaf, Tikrit, Mosul, Samara and Baghdad," said Dana Ahmed Majid, the security chief for Sulaymaniyah province.

     Qais Abu Assem, an al Qaeda member arrested just before the war, says the group never worked with Saddam Hussein, whom he calls an "infidel." He said al Qaeda welcomed the chance to face the Americans in Iraq.

     "We wanted them to come," he said in Arabic, "so we could have a clear, direct fight."

     U.S. commanders recognize the threat these fighters pose to American troops. They are training Iraqis, many of them former soldiers, to police the borders.

     But Abu Assem said al Qaeda is already firmly entrenched in Iraq.

     "There will be more attacks," he said with a chilling smile. "You will see."