Three Afghans killed in blast at U.S. base

A suicide bomber has killed three people in an attack on a U.S. base in Afghanistan, the same base that is believed to be used by the CIA and which a suicide bomber attacked three years ago killing seven CIA employees.

The Afghan Taliban claimed responsibility for the attack in the eastern town of Khost, saying they had sent a suicide bomber driving a van packed with explosives to the base.

"The target was those who serve Americans at that base," said Taliban spokesman Zabihullah Mujahid.

Afghanistan's NATO-led force said the bomber did not get into the base nor breach its perimeter. Police said the three dead were Afghans who were outside the base, which is beside a military airport.

The al Qaeda-linked Haqqani network, widely regarded as the most dangerous U.S. foe in Afghanistan, is active in Khost province, which is on the Pakistani border.

After more than a decade of war, Taliban insurgents are still able to strike strategic military targets, and launch high-profile attacks in the capital, Kabul, and elsewhere.

Three years ago, an al Qaeda-linked Jordanian double-agent killed seven CIA employees and a Jordanian intelligence officer in a suicide bombing at the same base in Khost, known as Forward Operating Base Chapman.

It was the second deadliest attack in CIA history.

Afghan police official General Abdul Qasim Baqizoy, the Khost police chief, said no CIA agents were hurt on Wednesday.

Afghan authorities are scrambling to improve security across the country before the U.S. combat mission ends in 2014.

Besides pressure from the Taliban, U.S.-led NATO forces also face a rising number of so-called insider attacks, in which Afghan forces turn their weapons on Western troops they are supposed to be working with.

On Monday, an Afghan policewoman killed a U.S. police adviser at the Kabul police headquarters, raising troubling questions about the direction of the war.

It appeared to be the first time that a woman member of Afghanistan's security forces carried out such an attack.

On Tuesday, Afghan officials said the woman has an Iranian passport and moved to Afghanistan 10 years ago. There was no suggestion that Iran was involved in the attack on the American.

Officials suspect she may have been recruited by al Qaeda or the Taliban, and had intended to also kill Afghan police officials.