Two U.S. soldiers were killed and eight others wounded as a missile hit the U.S. base at Shkin in Paktika province. Also two Pakistani truck drivers were killed as they left another U.S. base at Spin Boldak in Kandahar province after delivering fuel.
Taliban militants claimed both attacks, saying they meant to cut supply routes for U.S.-led forces in the country. Taliban spokesman Abdul Latif Hakimi said anyone working for the United States would be regarded as a target.
U.S. warplanes were not able to locate the attackers at Shkin but police in Spin Boldak said they had arrested five people.
Nearly 150 U.S. troops have been killed in Afghanistan since the start of the U.S. intervention in late 2001. Recently attacks have increased and all foreign nationals working in Afghanistan are at risk.