(CNN) -- NATO helicopters crossed into Pakistani airspace from Afghanistan in pursuit of insurgents over the weekend, killing 49 people, a spokesman told CNN Monday.
Crossing the border did not violate the International Security Assistance Force rules of engagement, Maj. Michael Johnson said.
Pakistan is very sensitive about United States-led military operations on its territory.
Johnson could not say whether the insurgents were killed in Afghanistan or Pakistan, or even whether the NATO helicopters fired their weapons in Pakistani territory.
They were responding to an insurgent attack on a remote Afghan National Security Force outpost in Khost province on Friday, ISAF said in a statement.
The statement suggests that the insurgents were shooting from the Pakistani side of the border.
CNN
