One of the dead was a U.S. soldier, military spokesman David Accetta said. Cheney, who stayed at Bagram overnight, is "fine," his spokeswoman Lea Anne McBride said.

The Taliban said it was responsible for the attack, the Associated Press reported, saying at least 19 people were killed and 11 injured.

Cheney visited Afghanistan and Pakistan to press those countries to improve security along their border to prevent a resurgence of the Taliban and al-Qaeda. The U.S. wants to counter al-Qaeda's attempts to re-establish training camps and to prevent any spring offensive by the Taliban from a remote mountainous region along Pakistan's 1,510-mile (2,430 kilometer) border with Afghanistan.

The incident took place at 10:30 a.m. Afghan time and the base was placed on temporary alert, Accetta said. Cheney stayed at the base after bad weather delayed his talks with Afghan President Hamid Karzai.

Cheney, who was close enough to hear the "loud boom" of the suicide bomb blast, said he won't let such an attack weaken the Afghan government.

"They've clearly tried to find ways to question the authority of the Afghan government," Cheney told reporters who flew with him on Air Force Two from Kabul to Muscat, Oman.

Suicide Bomber

"Striking at Bagram with a suicide bomber I suppose is one way to do that" adding that "it shouldn't affect our behavior at all."

The suicide bomber, who also died, appears to have been on foot, NATO's force in Afghanistan said in an e-mailed statement.

The bomber killed three people, including a U.S. service member, another member of the coalition military, and a contractor for the U.S. government whose nationality isn't known, the U.S. military said in an e-mailed statement. At least 27 people were wounded, including more than 20 Afghans.

The victims were all close to the bomber when he detonated outside the outermost gate of Bagram airfield, the military said.

"Our security measures were in place and the killer never had access to the base," Lieutenant Colonel James Bonner said in the statement. "When he realized he would not be able to get onto the base he attacked the local population."

Afghan Capital

After the attack, Cheney arrived in the Afghan capital at 12:15 p.m. local time and met Karzai at the heavily guarded presidential palace. In a brief appearance before reporters the two leaders talked about the harsh weather conditions and Cheney's eight-day long trip, making no mention of the attack.

Cheney's trip has taken him from Tokyo to Sydney to Muscat in Oman as well as Afghanistan and Pakistan. He flew back to Muscat today.

The U.S. and Italian ambassadors to Sri Lanka were injured today when artillery shells landed at an air force base during a visit to the east of the country. The Sri Lankan military blamed the rebel Liberation Tigers of Tamil Eelam for the attack.

Bagram air base is about 27 miles (47 kilometers) north of the capital, Kabul, and was used by Soviet troops during their occupation of Afghanistan. According to GlobalSecurity.org, Bagram has a 10,000 foot runway built in 1976 capable of handling large cargo aircraft and bombers.

Fixed-Wing Aircraft

The base is primarily used by the U.S. Army and Air Force, which operates helicopters and fixed-wing aircraft for U.S. operations against the Taliban and al-Qaeda. The U.S. has 15,000 soldiers as part of a North Atlantic Treaty Organization force in Afghanistan and another 12,000 involved in counter-insurgency operations and the hunt for al-Qaeda leader Osama bin Laden.

Cheney had breakfast today with Major General David Rodriguez, commander of the 82nd Airborne Division, and troops in their base mess hall.

The vice president arrived in Afghanistan from Pakistan where he pressed President Pervez Musharraf to increase operations against fighters hiding on the border.

The New York Times, citing unidentified administration officials, reported yesterday that Cheney was warning the Pakistani leader that aid to his country may be cut by Congress unless his forces take more aggressive steps against al-Qaeda.

Pakistan's government, in a statement released after the meetings, said Cheney expressed concern about the "regrouping of al-Qaeda in the tribal areas and called for concerted efforts in countering the threat."

Illegal Crossings

Pakistan, Afghanistan, U.S. troops and NATO forces will have to take "joint responsibility of stopping illegal crossings," the Pakistani statement said.

Bush earlier this month ordered an increase in the number of U.S. troops in Afghanistan and asked NATO allies to strengthen their commitment there.

U.K. Defense Secretary Des Browne announced yesterday that Britain will deploy 1,400 more soldiers in Afghanistan, bringing its contingent to 7,700. NATO's Afghan force now has about 34,000 soldiers from 37 countries.

NATO blames the loss of control over the border partly on a decision last year by Musharraf to give tribal leaders in the region greater autonomy. Musharraf and Karzai, meantime, have bickered over who's to blame for the Taliban's resurgence.

The Brussels-based International Crisis Group, an organization that monitors conflicts, said in a report last year the September 2006 agreement reached by Musharraf helped the Taliban because it limited Pakistani army operations.

Taliban Control

At least 4,000 Afghan civilians were killed in the fighting in 2006 as the Taliban sought to regain control of the southeastern provinces. Roadside bombings almost doubled last year and suicide bombings grew almost fivefold, making 2006 the most violent year since the Taliban were overthrown following the Sept. 11 attacks in the U.S.