Bagram, Afghanistan ? In what the Taliban claimed was an assassination attempt, a suicide bomber attacked the main gate of a U.S. military base Tuesday within earshot of Vice President Dick Cheney. The explosion killed 23 people, including two Americans, and delivered a propaganda blow that undercut the U.S. military and the weak Afghan government it supports.

The bomber struck about 10 a.m., and U.S. military officials declared a “red alert” at the sprawling Bagram Air Base while Cheney was rushed to a bomb shelter. Cheney, who had been stranded at the base overnight by a snowstorm, met with President Hamid Karzai in the capital before heading back to the United States via the Gulf state of Oman.

“I heard a loud boom,” Cheney told reporters aboard Air Force Two en route to Oman. “The Secret Service came in and told me there had been an attack on the main gate.”

Many of the victims were said to be Afghan truck drivers waiting to get inside the base. A dozen men – many of them sobbing heavily – left the base holding a stretcher bearing their loved ones wrapped in black body bags. Tears streamed down the face of one man sitting in the passenger seat of an SUV that carried another victim away.

A mile away

Although the bomber did not get closer than roughly a mile to the vice president, the attack highlighted an increasingly precarious security situation posed by the resurgent Taliban. Five years after U.S.-led forces toppled their regime, Taliban-led militants have stepped up attacks. There were 139 suicide bombings last year, a fivefold increase from 2005, and a fresh wave of violence is expected this spring.

The guerrillas, according to NATO officials, have the flexibility to organize an attack quickly and may have been able to plan a bombing at the base while Cheney was there after hearing news reports Monday that he was delayed by bad weather. The Taliban have attacked in the area north of the capital in the past even though people living in the Bagram area have not been supportive of the guerrillas. Col. Tom Collins, the top spokesman for the NATO force, said the Taliban had a cell in Kabul that could have traveled the 30 miles north to Bagram.

Asked if the Taliban were trying to send a message with the attack, Cheney said: “I think they clearly try to find ways to question the authority of the central government. Striking at Bagram with a suicide bomber, I suppose, is one way to do that. But it shouldn’t affect our behavior at all.”

Cheney was the highest-ranking U.S. official to stay overnight in either the Afghanistan or Iraq war zones.

President Bush was not awakened to be told about the attack, but received an update early Tuesday morning. White House press secretary Tony Snow said Bush’s first reaction was to ask if Cheney was OK.

Relatives carry the body of an Afghan man who was killed during a suicide attack at the main U.S. air base of Bagram, north of Kabul, Afghanistan. A suicide bomber killed at least 23 people and wounded about a dozen more Tuesday outside the main U.S. military base in Afghanistan during a visit by U.S. Vice President Dick Cheney. The Taliban claimed responsibility and said Cheney, who was not injured, was the target.

Cheney was the target

A message posted on a Web site used by militants said “a mujahid (holy warrior) … carried out a suicide attack in front of the second gate of the Bagram Air Base. … The target was Bush’s vice president, Dick Cheney.”

A purported Taliban spokesman, Qari Yousef Ahmadi, said Cheney was the target of the attack carried out by an Afghan named Mullah Abdul Rahim.

“We knew that Dick Cheney would be staying inside the base,” Ahmadi told The Associated Press by telephone from an undisclosed location. “The attacker was trying to reach Cheney.”

But it appeared unlikely the bomber would have been able to reach the vice president, who was in a “very safe and secure place” roughly a mile from the blast site, said U.S. spokesman Lt. Col. David Accetta.

The bomber, Accetta said, never tried to get by any U.S.-staffed security checkpoints and instead walked into a group of Afghans outside the base and detonated himself.

“To characterize this as a direct attempt on the life of the vice president is absurd,” Accetta said.

Cheney’s trip to Afghanistan – on the heels of a four-hour visit Monday to Pakistan – was not announced in advance. Snow said he did not know whether publicity about Cheney’s overnight stay at the base helped invite the attack – after the planned meeting Monday with Karzai was postponed.

Even though reaching the front gate of the U.S. base could have been achieved with relative ease, the idea of getting through U.S. security to attack Cheney was “far-fetched,” in the words of Maj. William Mitchell, a U.S. spokesman.

Nevertheless, Seth Jones, an Afghan expert at the RAND Corp. think tank, said the attack was a “stark reminder of the deteriorating security environment” in Afghanistan and was a propaganda boost for the Taliban.

Short-notice attack

“The attack also demonstrates the strength of the suicide network the Taliban and al-Qaida have in place,” Jones said. “To execute such an attack on such short notice requires a well-developed network of suicide bombers and handlers that can react quickly.”

Husain Haqqani, director of the Center for International Relations at Boston University and a former adviser to three Pakistani prime ministers, said the attack “does not reflect well on the Afghan government’s ability to maintain security.”

The bombing sends the message that the Taliban threat “is greater than the U.S. has considered it,” he said.

Karzai’s office said 23 people were killed, including 20 Afghan workers waiting outside the base. Twenty other people were injured, it said.

NATO said nine people had been killed, including a U.S. soldier, a U.S. contractor and a South Korean soldier, but Collins said the numbers from Karzai’s office were probably “close to the truth.”

AP reporters at the scene saw 12 bodies being carried in black body bags and wooden coffins from the entrance of the base – where they were taken after the bombing – and into a market area where hundreds of Afghans, almost all men, had gathered to mourn.

Khan Shirin, a private security guard, sobbed in the back of a pickup truck and kissed the body bag bearing his relative, Parvez, who was a truck driver and the representative of a transport association that hauls goods for the U.S. base.

“How will I tell your mother and father and return your body to your home?” he said, wiping his tears away. “You’ve left us.”

During their private hourlong meeting, Cheney and Karzai spoke about the “problems coming from Pakistan,” said an Afghan government official, a reference to cross-border infiltration by militants who launch attacks in Afghanistan.

“We understand now that the U.S. government realizes that in order to stop terrorism in Afghanistan and to stop terrorist attacks in Afghanistan, there must be a clear fight against terrorism in Pakistan,” said the official, who spoke on condition of anonymity because of the sensitivity of the matter.

Karzai’s office said Cheney told Afghan leaders the United States “will continue its assistance to Afghanistan.”

A senior administration official told reporters on Cheney’s airplane that Bush had wanted Cheney to travel to the region because of “the continuing threat that exists in this part of the world.”