The U.S.-led coalition said it used artillery and aerial drones against attackers who opened fire on forces operating inside Afghanistan. It said coalition forces did not enter Pakistan.
The incident late Tuesday followed a reported clash between Afghan forces and coalition forces and Taliban militants in the same area. The Taliban said eight of its fighters died in the skirmish.
The Pakistani army said the coalition airstrike hit a post of the paramilitary Frontier Corps and was a "completely unprovoked and cowardly act" that "hit at the very basis of cooperation" in the war on terrorism.
It launched a strong protest and reserved "the right to protect our citizens and soldiers against aggression," the military said in a statement. The statement said the clash in the Mohmand tribal region "had hit at the very basis of cooperation" between the allies in the war on terror.
