KARSHI-KHANABAD AIR BASE, Uzbekistan -- The din of bulldozers and steamrollers competes with the roar of aircraft engines at this U.S. outpost for the anti-terror campaign in Afghanistan. The Americans are digging in for the long haul -- but walking on eggshells.
Based in this majority Muslim nation of 26 million, they are anxious not to offend their hosts or build anything that looks permanent. And beyond the concrete walls surrounding this ex-Soviet base, nearby China, Russia and Iran are all nervously watching the American presence on their doorstep.
More than 2 1/2 years after Uzbekistan allowed U.S. forces to use the base -- the first U.S. deployment in the former Soviet Union -- it remains a key transit and support point for operations in Afghanistan.
Karshi-Khanabad air base, known as K2, is 90 miles from the border and two hours' flying time from anywhere in Afghanistan. It's also the main hub for civilian contractors from Halliburton Co. subsidiary KBR to catch military flights into Afghanistan.
Although the base is generally off-limits to journalists, the military recently allowed the Associated Press to visit.
The United States has spent $5 million to double the amount of parking space for planes, and about 20 lumbering C-130-type transport aircraft are based at K2.
New barracks are going up, so all the base's 1,750 personnel will be out of tents by fall. Also coming soon are an expanded $500,000 fitness center, a new $1 million dining hall and a movie theater. Roads are being paved.
All the bustle at K2 makes it appear it will figure strongly in the Pentagon's post-Cold War realignment from bases in Europe closer to the 21st century's hot spots. But U.S. officials and base commanders say no long-term plans have been made, and the new buildings are mostly prefabs that can be removed quickly.
"Whatever construction we have here is for an enduring presence, but not long-term," said base commander Army Lt. Col. Neal Kemp.
Uzbek President Islam Karimov has said the Americans will stay only as long as Afghan operations continue. But other Uzbek officials more recently have left open the question of a longer presence.
K2, which is also home to Uzbek fighter planes, served as a main hub for U.S. special operations in Afghanistan and once hosted AC-130 gunships and other combat aircraft. U.S. commanders say no combat operations are now taking place from K2.
In Russia, some hard-line politicians have called for the Americans to leave as soon as possible.
The Chinese have also grown uneasy; the other U.S. regional base is near Bishkek, the capital of Kyrgyzstan, just 175 miles west of China.
Given those sensitivities, K2 still remains extremely low-profile and tightly secured. Enlisted men aren't allowed to visit the nearby city of Karshi. Officers who go off base on business wear civilian clothes.
"We are not going to be the ugly Americans that give them a bad opinion of the United States," said U.S. Air Force Col. Timothy Vining, commander of air operations at K2.
Jobs are scarce in nearby Karshi, so the employment of some 500 Uzbeks at the base is welcome, said Utkir Normominov, who earns $200 a month supervising janitors at K2.
The 22-year-old Uzbek wears a Boston Red Sox cap and studies English at the university in Karshi.
"America trusts me," he said. "The U.S. Army trusts me."