Special forces were fired at by two men armed with AK-47 assault rifles in Deh Rawud, a town in the central province of Uruzgan, early on Thursday. One of the assailants was killed and the other escaped, the statement said.
Later in the day, eight people wearing civilian clothes and carrying AK-47s and light machineguns opened fire on US special forces north of their forward base near the eastern city of Khost.
An A-10 aircraft and Apache helicopter were called in as support, but there were no immediate reports of casualties after the helicopter fired 30 30mm rounds and 14 rockets.
The statement also said U.S paratroopers had launched air assaults on four targets northeast of Khost in 24 hours to prevent hostile forces establishing positions near the city.
Khost has seen frequent clashes between fighters loyal to the the local governor and a renegade warlord, and US forces have been the target of regular small-arms and mortar attacks in a region where there is considerable opposition to their presence.
Nearly 8,000 US troops are leading a coalition of forces in Afghanistan.—Reuters