The U.S. military is losing momentum in the war on terrorism in Afghanistan because the remnants of al Qaeda and the Taliban have proven more successful in adapting to U.S. tactics than the U.S. military has to theirs, the chairman of the Joint Chiefs of Staff said this week.

Gen. Richard B. Myers also said there is a debate taking place within the Pentagon about whether the United States needs to change its priorities in Afghanistan and de-emphasize military operations in favor of more support for reconstruction efforts.

"I think in a sense we've lost a little momentum there, to be frank," Myers said in after-dinner comments Monday night at the Brookings Institution. "They've made lots of adaptations to our tactics, and we've got to continue to think and try to out-think them and to be faster at it."

Myers, the nation's top military officer, suggested it may be time for the military to "flip" its priorities from combat operations aimed at hunting down al Qaeda and Taliban fighters to "the reconstruction piece in Afghanistan," a notable shift in priorities for an a Pentagon that has eschewed nation-building exercises.

The CIA, in a recently released assessment, called security "most precarious in smaller cities and some rural locations" and said: "Reconstruction may be the single most important factor in increasing security throughout Afghanistan and preventing it from again becoming a haven for terrorists."

Afghan President Hamid Karzai recently launched an anti-corruption campaign aimed at cracking down on provincial leaders who continue to challenge the authority of the country's central government.

Myers issued his call for faster and more flexible approaches in the counterterrorism war a day after the United States conducted its first-ever airstrike in Yemen, using an unmanned aircraft to do it. A CIA-operated Predator drone on Sunday attacked a vehicle believed to be carrying six al Qaeda members with Hellfire missiles, obliterating the vehicle and its passengers. Yemeni authorities said among the passengers was Abu Ali al-Harithi, a senior al Qaeda leader and one of the terrorist network's top figures in Yemen.

Andrew F. Krepinevich Jr., a retired Army colonel and Pentagon consultant who directs the Center for Strategic and Budgetary Assessments, said Monday's attack in Yemen cannot mask the continuing instability in Afghanistan and the lack of strong counterterrorism relationships between the United States and countries such as Malaysia and Indonesia.

Wayne A. Downing, a retired Army general who until June served as the White House special adviser on combating terrorism, disagreed, saying that the United States has matched al Qaeda in adjusting its operations. "Getting this guy in Yemen was huge -- and a significant escalation in a different place," he said.

Downing said he expects the military to play a smaller role in the war on terrorism, with diplomacy and intelligence cooperation becoming more important. He also predicted that actions like the one in Yemen will be more characteristic of the campaign.

Ivo H. Daalder, a senior fellow at the Brookings Institution, called a shift in priorities by the military in Afghanistan away from pursuing al Qaeda and toward reconstruction "noteworthy and extremely important." But Daalder said he doubted whether Myers or Defense Secretary Donald H. Rumsfeld would commit U.S. forces to "tackling the fundamental security problem in Afghanistan, which is not al Qaeda, but a byproduct of the way we fought -- arming the warlords."

"What needs to be done is to take away the power of the warlords and give it to the central government, and that requires real military force," Daalder said. "Are we prepared to take on the very guys we empowered? I don't see any evidence that is the case."

In his remarks at Brookings, Myers said al Qaeda has proven to be an agile adversary, adapting its electronic communications to prevent intercepts and securing the way it passes money. His comments, released by Brookings on Wednesday, reflect a concern that many senior U.S. officials have expressed privately in recent months that the military establishment has been too slow to adapt in its response to the al Qaeda threat, both in its special operations tactics and its weapons procurement.

One official close to Rumsfeld said this week that, in his view, the military still is largely geared to changing at the glacial pace of the Cold War, during which shifts in military doctrine and weaponry in the Soviet Union occurred generationally. Al Qaeda and its allies have shown "an ability to change by the month," the official said.

A detailed analysis just released by the U.S. Army War College reported that al Qaeda fighters have been quick to adapt to the high-tech weaponry the United States used in its attack on the network. When the United States first began bombing in Afghanistan last October, the report said, Taliban and al Qaeda fighters made easy targets, even standing on ridges where they were visible to Special Operations spotters miles away.

Stephen Biddle, the report's author, wrote that by March, during the last major U.S.-led offensive against al Qaeda in southeastern Afghanistan, "Al Qaeda forces were practicing systematic communications security, dispersal, camouflage discipline, use of cover and concealment, and exploitation of dummy fighting positions to draw fire and attention from their real positions."

Added one senior officer: "It's the general consensus within the [special operations] community that al Qaeda is extremely adaptive and very cagey. These guys are not weekend terrorists."

The military isn't keeping up with al Qaeda, Gen. Richard B. Myers said.Soldiers from the U.S. Army 82nd Airborne Division remove rockets Sunday from a home in the village of Naray in southeastern Afghanistan.