The U.S. military's plan to establish eight to 10 relatively small regional bases across Afghanistan reflects a belief that security is improving and is good enough in those areas to warrant a transition from combat sweeps to "stability" operations, senior defense officials said last week.

But the decision to create "joint regional teams" that will each include about 60 U.S. troops, as well as Special Forces civil affairs troops, USAID officials and diplomatic personnel, also shows the Pentagon still thinks that the overall security situation in Afghanistan remains fragile and that new efforts must be made to bolster the fledgling government of Afghan President Hamid Karzai.

An American soldier was shot and killed by suspected al Qaeda fighters Saturday while patrolling in eastern Afghanistan. The incident marked the first death of a U.S. serviceman by hostile fire since May. Another soldier was injured Friday in a rocket attack on a U.S. base in eastern Afghanistan, and a third was wounded in a training accident in southern Afghanistan the same day. On Tuesday, a grenade attack in Kabul, the capital, wounded two U.S. servicemen and their Afghan interpreter.

"As President Karzai is fond of saying, security is the first priority," said Joe Collins, deputy assistant secretary of defense for stability operations. "You can't have reconstruction without security, and in the end, you won't have security without reconstruction."

Collins said that "moderate to good" security exists in 26 of 33 Afghan provinces, with combat sweeps against small remnants of Taliban and al Qaeda forces only taking place along the eastern border with Pakistan and in other isolated areas in the south.

With the first joint regional team being established in Gardez in Paktia province in southeastern Afghanistan, Collins said the primary focus of U.S. military personnel would be on maintaining security and establishing partnerships with local government leaders and soldiers from the newly trained Afghan National Army, who in many cases will be attached to the regional teams.

Collins said he had little patience for some leaders of non-governmental relief agencies who have expressed concerns about the blurring of lines between soldiers and aid officials.

"This is not a civil war," Collins said. "If there are NGOs [non-governmental organizations] who don't want to deal with coalition forces, that's fine. But coalition forces are the ones who are out there making sure people who are against progress in Afghanistan are being taken [care] of."

Collins said that while some Special Forces soldiers will be involved in civil affairs projects, the focus of most regular troops will be on security, not reconstruction. "The vast majority of project work is being funded by USAID and the State Department, and that's going to continue," he said. "We are not sending these teams out there to put GIs to work digging ditches for irrigation."

Andrew F. Krepinevich Jr., a retired Army colonel and Pentagon consultant who directs the Center for Strategic and Budgetary Assessments, said the Army has had "an allergy" to such nation-building missions dating back to its experience in Vietnam.

"At the same time, this is something the Army needs to get good at, because we can't allow weak states to lapse back into conditions that spawn terrorists in the first place," he said. "And it will be the same thing in Iraq. If there is a war and we do win, the mission will be to try to bring an artificial state back together again."

William J. Durch, a peacekeeping specialist at the Henry L. Stimson Center, a Washington think tank, also questioned whether the regional teams will be large enough to do much more than protect themselves against possible attack.

"It's a step in the right direction," Durch said. "My concern is that it's not going to have enough muscle to make it work. And our policy in the [Persian] Gulf is undercutting this thing big time -- it's sucking the air and the policy attention out of Afghanistan, and it's a half-finished job."

Ivo H. Daalder, a senior fellow at the Brookings Institution, credited the Bush administration -- whose leaders have been opposed to nation-building -- for acknowledging that "military forces can do other things than fighting wars -- that they are a critical and integral part of bringing about peace."

But he questioned why the Pentagon has chosen to use dual systems for stability operations in Afghanistan, with 5,000 troops from the International Security Assistance Force (ISAF) confined to the Kabul area and new U.S.-led bases being established in the rest of the country.

Collins responded that none of the countries participating in the ISAF has expressed interest in operating beyond a 240-square mile area around Kabul. He also said that the joint regional teams have more than enough combat power to defend themselves and engage in security patrols throughout the countryside, given their ability to call in large numbers of reinforcements and massive amounts of air power.

Indeed, the impetus for establishing new security teams in regional areas came from the Central Command, not from the Pentagon's policy shop, Collins said.

Jim Wilkinson, a Central Command spokesman, said concerns about whether the regional teams would be capable of defending themselves "do not reflect reality on the ground" in Afghanistan, where security is improving every day.