Kabul, Afghanistan ? President Hamid Karzai condemned a U.S. airstrike Thursday that Afghan officials said killed 10 border policemen. Sixteen other people died in violence across the country, including an American soldier slain by a Soviet-era land mine.

The U.S. military said it was investigating the airstrike in southeastern Afghanistan, but believed it had struck insurgents fleeing the scene of an attack on U.S. and Afghan troops.

Two suicide bombers targeted U.S. and NATO troops, seriously wounding one American soldier and killing an Afghan civilian. A purported spokesman for the Taliban said it would launch more such attacks in the future.

Afghanistan is going through its worst period of violence since the U.S.-led invasion that ousted the hard-line Taliban regime in late 2001 for hosting Osama bin Laden.