The U.S. military has deployed artillery to Afghanistan for the first time, giving ground forces the ability to counter mortar and rocket attacks by al Qaeda and Taliban fighters. A senior military official said the Army has deployed six 105mm howitzers at the main U.S. base in the southern city of Kandahar as part of an effort to bolster protection of the 8,000 American troops in the country.

The howitzers, equipped with counter-fire radar, enable U.S. forces to pinpoint the location of enemy mortar and rocket fire and respond with artillery shells. A spokesman for Central Command, which is overseeing the war, declined to comment on the reason for the deployment yesterday. It involves elements of the 82nd Airborne's 319th Field Artillery Regiment.

From the outset, the military has taken note of the Soviet military defeat in Afghanistan in the 1980s, when large numbers of Soviet forces were confined to garrison and harassed and attacked by Afghan mortar and rocket fire. In response, the Pentagon opted to keep the U.S. military presence in the country relatively small, one reason ground commanders did not bring artillery -- the heaviest component of any Army division -- into Afghanistan before now.

But faced with a volatile security situation -- a gunman tried to assassinate Afghan President Hamid Karzai last week on the same day a bomb killed 23 people in Kabul -- commanders realize that U.S. forces are going to be in Afghanistan for the foreseeable future at vulnerable bases.

Hundreds of U.S. troops launched a sweep yesterday through the mountains in eastern Afghanistan's Paktia province on the Pakistani border, searching for members of the al Qaeda network and Afghanistan's ousted Taliban militia.

Anthony H. Cordesman, a former Pentagon official who is a military and diplomatic analyst at the Center for Strategic and International Studies, said a debate is developing within the U.S. military between those who believe in continuing a hunt for al Qaeda and Taliban remnants, and those who believe the United States has reached a point of diminishing returns and should turn over security to Afghanistan's central government, regional leaders and an international peacekeeping force in Kabul.

But as long as the U.S. military has 8,000 troops in Afghanistan, Cordesman said, adding artillery to bolster force protection makes good sense. "This to me is a pragmatic gesture -- and it certainly does reflect the fact that things aren't perfectly secure," he said.

Michael E. O'Hanlon, a senior fellow and military analyst at the Brookings Institution, said al Qaeda fighters in Afghanistan have shown themselves adept at exploiting what little opportunities they have been given by U.S. forces. "If they are able to lob a shell at you and run, you can't call in air power quickly enough to go after them," O'Hanlon said. "The only way to deprive them of that is to be able to respond really fast, and artillery is very quick in its response time."

Barnett R. Rubin, a New York University expert on Afghanistan, said the Army's decision to send artillery to the country "validates" a belief he formed during a recent trip there that armed resistance to the U.S. military and the Karzai government is "becoming better organized and more effective."

"They can't gain any military victories," he said. "What they can do is harass U.S. troops more, in the hopes of producing more casualties, and they can engage in acts of terror -- either assassination attempts against key Afghan leaders, or acts of terrorism against Afghan civilians."

The addition of artillery, Rubin said, seems to be a natural response by a military that "sees itself as a war-fighting military, fighting a low-level counter-insurgency war."

"What I think is much more necessary is a reconfiguration of U.S. force structure and mission so it puts a much higher priority on promoting the security of the Afghan government and the Afghan people," he said. "Artillery doesn't do anything to increase the security of Afghans."

Retired Army Maj. Gen. Bob Scales, a former artillery commander in the 82nd Airborne, said 105mm howitzers would enable commanders to create a defensive "arc," with a radius of eight to 10 miles, around U.S. bases. With counter-mortar radar, Scales said, "you can have rounds going back at the [enemy] mortar before that [incoming] round actually lands on you."

Beyond force protection, retired Army Col. Robert Killebrew said the addition of artillery to Afghanistan is also a clear sign that ground commanders in the 82nd Airborne believed the Central Command erred in a major offensive against al Qaeda in March when it sent elements from the 10th Mountain and 101st Airborne divisions into the eastern mountains without artillery support.

"You don't deploy infantry without some kind of fire support," Killebrew said. "The mortar duels that they got involved in up on the ridges there were a clear signal that someone had forgotten that lesson. Air support wasn't very effective in suppressing those [enemy] mortars."