The 38,000-pound Caiman armored vehicles stopped at the fringe of this rural village and disgorged a group of U.S. soldiers and Iraqi police. Their mission: seek out and detain a half-dozen men wanted by the Iraqi government for terrorism-related offenses.

The group moved slowly into the sprawling community, at first giving the impression of an ordinary presence patrol, then veering sharply and rapidly into selected houses to search for their targets. The Caimans followed behind, providing security and ready to give devastating covering fire, if necessary, with their turreted .50 caliber machine guns.

The Caimans were ideal for the mission. Their V-shaped armored undercarriage deflects the force of improvised explosive devices, the single highest cause of U.S. casualties in the Iraq war and a very real danger when traveling off tarmac roads. Side and top armor protects occupants from rocket-propelled grenades and small arms fire. With a height of about nine feet from ground to roof, crew have a good overview of an area while troops are on the ground. And its large passenger interior seats six or seven soldiers and, even with gear figured in, leaves room for several detainees to sit on the floor.

In this instance the space wasn't needed. Only one suspect was rolled up.

"All the cells that were operational when we came to this area for the most part have been disrupted," said a U.S. intelligence officer with 2nd Battalion, 302nd Field Artillery Regiment, 101st Airborne Division. "They've been so disrupted over the last year, I have a hard time on a weekly basis finding guys to target. We're having to use a lot more different intelligence methods to find these guys, because they're getting smarter and the few that are left are a lot better at what they do.

"It's survival of the fittest. The guys who are dumb are either dead or detained," he said.

The 302nd, which has taken on infantry duties, operates in an area of Salahaddin province near Joint Base Balad, the largest and busiest aerial port in Iraq and located about 50 to 60 miles northwest of Baghdad. If U.S. forces are to maintain a presence in Iraq after a general drawdown Balad would likely figure prominently.

The U.S. Air Force portion of the base features two runways -- one 11,200 feet and the other 11,300 feet -- and scores of hardened shelters for its complement of F-16 jet fighters, facilities for protection and maintenance of HH-60 Pave Hawk helicopters, Kiowa scout helicopters and UH-60 Blackhawks.

MQ-1 surveillance and attack Predators, which can carry ordnance, and MQ-9 Reaper Unmanned Aerial Vehicles also fly out of JBB, roaming not only Salahaddin province in search of terrorists but neighboring provinces as well, such as Diyala to the east where al-Qaida in Iraq leader Abu Musab al-Zarqawi was killed by a Predator while traveling in a car with his aides.

Balad is also a major hub for troops and cargo entering or leaving Iraq or moving within the country and without. The 332nd Air Expeditionary Wing, which runs the base, says on a monthly basis it handles 950 cargo flights (mainly C-17s), 12,000 tons of cargo and about 19,000 passengers.

A Level 1 trauma hospital is located on the 25-square-kilometer base, which during the regime of Saddam Hussein was the site of Iraq's air force academy.

The other portion of the base is LSA -- Life Support Area -- Anaconda from which U.S. Army units operate. In LSA Anaconda there's transit billeting, dining facilities the size of two football fields, a large MWR -- Morale, Welfare and Recreation -- facility with Internet and telephone connections and game rooms, as well as U.S. fast food concessionaires. In short, JBB is an American mini-city in the Iraqi heartland.

Insurgents frequently target the mini-city with mortars, but U.S. officers say the number of direct fire attacks is down in recent months -- from 32 to 40 per month a year ago to about nine now -- due to constant patrolling of surrounding areas by U.S. and Iraqi security forces, increased tips from local citizens and establishment of armed community watch groups, the U.S.-paid Sons of Iraq, formerly called Concerned Local Citizens -- CLC.

"Seven months ago it was really bad around here," said 1st Lt. Michael Handlan, a platoon leader with the 302nd. "There were a lot of bad guys and we were constantly finding IEDs (improvised explosive devices). There are still some around, but they can't do much because of the patrols and the CLCs."