Pakistan's army said Wednesday that a U.S.-led coalition airstrike along the volatile Afghan-Pakistan border killed 11 of its paramilitary troops, condemning it as an act of aggression that "hit at the very basis of cooperation" on the war on terror.

NATO is struggling to remain unified over the war in Afghanistan after the United States raised concerns that some members of the Western alliance were not willing to let their troops "fight and die" to defeat the Taliban.

Four heavily armed militants attacked a hotel popular with foreigners in Kabul, Afghanistan, on Monday, killing at least six people in a brazen Taliban-backed attack apparently targeted at Western workers, witnesses and a Taliban spokesman said.