Taliban fighters attacked part of a U.S. military outpost in the eastern Afghan province of Nangarhar on Monday, officials said, less than a week after targeting a Polish base in a nearby province.
Attacks on Afghan security forces and civilians have also mounted this week killing dozens and adding to fears the drawdown of foreign troops, most of whom are due to leave the country by the end of next year, is allowing insurgents to regain lost territory.
"In a parking lot used by Americans there was a huge blast and after that a massive attack... A number of our heroes are fighting," said Taliban spokesman Zabihullah Mujahid in an email.
The attack prompted police to shut part of a highway between the provincial capital and Torkham district near the border with Pakistan, a security source said. The base itself had not been penetrated.
No casualties had been reported, provincial spokesman Ahmad Zia Abdulzai said.