The Taliban has claimed responsibility for an attack that killed four U.S. troops in Afghanistan, hours after the U.S. announced it was opening formal talks with the insurgent group.
A Taliban spokesman said the group fired two rockets into the Bagram air base on Tuesday.
Earlier, the U.S. said direct negotiations with the Taliban will begin Thursday in Doha, the capital of Qatar, in a push to establish a framework for ending more than a decade of war in Afghanistan.
Senior U.S. State Department and White House officials are expected to meet with a Taliban delegation, in what authorities are describing as preliminary talks.
President Barack Obama, speaking Tuesday at a G8 summit in Northern Ireland, called the Qatar talks "a very early first step," and cautioned that he expects "there will be a lot of bumps in the road" .
Afghan President Hamid Karzai's government is not expected to participate in the initial round of the Doha talks.
But officials say Thursday's talks are expected to lead to a meeting between the Taliban and a peace council established by the Afghan leader. To date, the Taliban has refused to talk publicly with the Karzai government.
President Karzai said Tuesday his government will send envoys to Qatar to try to open peace talks in Kabul with the Taliban.
"The principles are that the talks, having begun in Qatar, must immediately be moved to Afghanistan; second, that the talks must bring about an end to violence in Afghanistan; third, that the talks must not become a tool for any third country for exploitation with regard to its or their interests in Afghanistan."
Mr. Karzai commented in Kabul, during a ceremony in which Afghan forces took over responsibility for security for the entire country from the NATO military coalition set to leave the country next year.
In a VOA interview, foreign policy expert John Feffer of the Institute for Policy Studies said it appears there is some resistance to talks within the ranks of the Taliban, with some members of the group taking a wait-and-see attitude.
"They are interested in seeing who will emerge to replace Karzai and they are interested in seeing how much control they can get on the ground, especially with the increased violence that has taken place recently."
Earlier Tuesday, a senior U.S. official said the Taliban and other insurgent groups need to break ties with al-Qaida, end violence and accept Afghanistan's constitution, for the reconciliation process to move forward.
He also said leaders in neighboring Pakistan understand there can be no stability in their country without stability in Afghanistan. The official said Pakistan's support of the peace process is in keeping with its national interests.