The two Apache attack helicopters from the NATO-led International Security Assistance Force (ISAF) crossed the border from eastern Afghanistan on Friday after the insurgents attacked a remote Afghan security outpost in Khost province.
ISAF spokesman Sergeant Matt Summers confirmed that the helicopters had attacked after crossing into Pakistan. He did not comment on which countries’ forces were involved, but the United States is the only coalition member that uses Apaches.
The United States regularly uses pilotless drone aircraft for missile strikes in Pakistan’s borderlands, known to be a haven for militant groups including the Afghan Taliban who launch cross-border attacks from Pakistan’s northwest.
However, manned military flights across the border are extremely rare.
ISAF said in a statement issued late on Sunday that the helicopters were following its rules of engagement when they crossed into Pakistan.
Two Kiowa helicopters returned to the area on Saturday and killed at least four more insurgents, the statement said.