It was impossible for the strongest military in the world to secure Iraq’s vast borders. And, as of next month, the job will belong to Fatih and his ragged comrades. The U.S. Army’s Third Armored Cavalry Regiment, which guards 500 miles of rugged semidesert along the Syrian, Saudi and Jordanian borders, is pulling out at the end of the month. Other U.S. Army troops are leaving Iraq, too, including the 101st Airborne Division, which controls 100 miles of the Syrian border and Iraq’s frontier with Turkey. As the troops withdraw, smaller contingents of both the U.S. Army and the Marines will replace them, but the job of protecting the country’s perimeter will fall mostly to a poorly equipped and hastily trained Iraqi police force. Both Iraqis and the Coalition have reason to worry. Analysts believe the most devastating attacks in the war against the occupation–the suicide bombings that have killed hundreds of Iraqis–are the work of outside infiltrators who have passed virtually at will across the unprotected borders.

Critics say the Americans have only themselves to blame. “There was this idea that we could abolish the Army and security forces, and then [we were surprised that] there was no control of the border,” says one State Department official who worked on the postwar plan. U.S. forces lacked the manpower to secure the borders themselves and, in the vacuum, the foreign jihadis moved in. European law-enforcement officials say Al Qaeda has established a network across Europe to recruit foreign fighters, providing them with fake passports, training and cash, and guiding them along infiltration routes into Iraq. Military sources say that tens of thousands of dollars in cash to fund the insurgency and some weaponry–including Chinese-made missiles capable of penetrating an M1 Abrams tank–are being smuggled into Iraq.

Nobody knows how many foreign fighters have entered the country. While some Iraqi officials believe the number could be as high as several thousand, U.S. military sources say foreigners probably number only 10 percent of the 3,000 to 5,000 insurgents. Yet even a small number of jihadis can do tremendous damage. “If you’ve only got 50 foreign fighters coming through, that’s a lot,” says Col. Greg Reilly, commander of Tiger Base, an outpost 17 miles from the Syrian border.

Both the Americans and the Iraqis are overextended. The Third Armored Cavalry Regiment conducts satellite surveillance and air patrols. But they remain preoccupied with battling local insurgents. For the most part, the troops have turned over responsibility for guarding the Syrian frontier to two battalions of Iraqi Border Police, or about 420 men. They are based in a few dozen observation posts that extend for only about 15 miles in either direction from the main Syrian-border crossing at Al Qaim. That leaves 70 miles of the border zone completely unguarded. The cops undergo a two-week training course and receive salaries of $160 a month, generous in Iraq. But their equipment is meager, their mobility limited and their motivation is often low. “The Coalition Provisional Authority hasn’t given them anything,” says Col. Antonio Aguto, who spent some of his regiment’s own funds on vehicles and uniforms.

The Coalition is scrambling to bring the Iraqis up to speed. Last month Iraq’s Governing Council approved the creation of a new homegrown intelligence unit to crack down on infiltrations and root out foreign fighters. The controversial outfit–to be funded by the U.S. government and trained by the CIA–will consist of hundreds of agents, including some former members of the Mukhabarat, Saddam Hussein’s dreaded security apparatus. The Third Armored Cavalry Regiment will put another battalion of border police on the Syrian frontier before it withdraws. But troops say more is needed, including computers at official crossings to verify the identities of everyone attempting to enter Iraq legally. “Nineteen hijackers slipped into the United States without any problem,” says Capt. Justin Brown, commander of Checkpoint Apache, a Syrian-border crossing. “You can imagine how easily [a terrorist] can cross at primitive border points like this one.”

Right now Iraq’s border security depends on the vigilance of well-intentioned police like Fatih. Hoisting his Kalashnikov over his shoulder and venturing into the frigid night on foot patrol, he says his men are desperate. “We need night-vision goggles, we need vehicles to patrol,” he pleads. But it’s likely many more jihadis will cross Iraq’s frontiers before his pleas are answered.