A multi-pronged militant assault on a small, remote U.S. base close to the Pakistan border killed nine American soldiers and wounded 15 Sunday in the deadliest attack on U.S. forces in Afghanistan in three years, officials said.

The attack on the American troops began around 4:30 a.m. and lasted throughout the day. Militants fired machine guns, rocket-propelled grenades and mortars from homes and a mosque in the village of Wanat in the mountainous northeastern province of Kunar, NATO's International Security Assistance Force said in a statement.

"Although no final assessment has been made, it is believed insurgents suffered heavy casualties during several hours of fighting," NATO said in a statement.


U.S. officials say militant attacks in Afghanistan are becoming more complex, intense and better coordinated than a year ago. Monthly death tolls of U.S. and NATO troops in Afghanistan surpassed U.S. military deaths in Iraq in May and June. And last Monday, a suicide bomber attacked the Indian Embassy in Kabul, killing 58 people in the deadliest attack in the Afghan capital since 2001.