A suicide bomber killed and wounded two dozen people outside the main US military base in Afghanistan on Tuesday during a visit by US Vice President Dick Cheney. The Taliban claimed responsibility and said Cheney was the target. The blast happened outside the base at Bagram, north of the capital Kabul. Cheney's spokeswoman said he was fine, and the US Embassy said the vice president later met with President Hamid Karzai in Kabul. There were conflicting reports on the death toll. Provincial Gov. Abdul Jabar Taqwa said 20 people were killed, but NATO said initial reports indicated only three were killed, including a US soldier, a South Korean coalition soldier and a US government contractor whose nationality wasn't immediately known. NATO said 27 people were also wounded. It was unclear why there was such a large discrepancy in the reports. Maj. William Mitchell said it did not appear the explosion was intended as a threat to the vice president. "He wasn't near the site of the explosion," Mitchell said. "He was safely within the base at the time of the explosion." A purported Taliban spokesman, Qari Yousef Ahmadi, however, said Cheney was the target of the attack, which Ahmadi said was carried out by an Afghan, Mullah Abdul Rahim from Logar province. "We knew that Dick Cheney would be staying inside the base," Ahmadi told AP telephone from an undisclosed location. "The attacker was trying to reach Cheney." The explosion happened near the first of at least three gated checkpoints vehicles must pass through before gaining access to Bagram, meaning the attacker did not get near Cheney's location. "We maintain a high-level of security here at all times. Our security measures were in place and the killer never had access to the base," said Lt. Col. James E. Bonner, the base operations commander. "When he realized he would not be able to get onto the base he attacked the local population." It was not the first attack apparently aimed at a top US official in Afghanistan. In January last year a militant blew himself up in Uruzgan province during a supposedly secret visit by the US ambassador, killing 10 Afghans. Ajmall, a shopkeeper, said the "huge" blast shook a small market where he has a stall about 500 meters from the Bagram base. Ajmall, who goes by one name, said those wounded in the blast were taken inside the US base for treatment. South Korea's Defense Ministry said one of its troops stationed in Bagram, Pfc. Yoon Jang-ho, 27, was killed in the explosion. South Korea has about 200 engineers and medics in Bagram. Cheney, who spent the night at Bagram, left the base about two hours after the 10 a.m. blast. The explosion sent up a plume of smoke visible by reporters inside the base traveling with Cheney, and American military officials declared a "red alert" inside the base. "The vice president is fine," said his spokeswoman, Lea Anne McBride. Cheney later flew by plane to Kabul, 50 kilometers south of Bagram, to meet Karzai after a planned meeting on Monday was canceled because of bad weather that prevented the vice president making the trip to the capital. Cheney was met by armed guards with guns drawn on the tarmac and was rushed by ground convoy to the presidential palace. Cheney and Karzai were expected to discuss the surge in violence in Afghanistan. Five years after their fundamentalist regime was toppled, Taliban-led militants have stepped up attacks and Afghan, US and NATO forces are bracing for a fresh wave of violence in the spring. There were 139 suicide bombings last year, a five-fold increase over 2005, and Rodriguez has said he expects the number of suicide bombs to rise even further in 2007.