Afghanistan ? Nine U.S. soldiers were killed in heavy fighting Sunday at a military base in eastern Afghanistan near the Pakistani border, according to a Western official. The attack was the deadliest against U.S. forces in the country since 2005.

The clash began when insurgents in a nearby village attacked a joint Afghan and American military outpost in Konar province early Sunday morning, NATO said in a statement. The insurgents fired on the base with machine guns and rocket-propelled grenades for several hours, injuring 19 Afghan and NATO troops.

NATO said in a statement that the fighters used “homes, shops and the mosque in the village of Wanat for cover” and said the insurgents “suffered heavy casualties” in return fire.

Attacks in eastern Afghanistan have increased sharply in recent months as insurgents have streamed across the country’s mountainous 1,500-mile border with Pakistan as part of an offensive declared this year by top Taliban leaders in Pakistan.