WASHINGTON (AP) — NATO forces may have been lured into attacking friendly Pakistani border posts in a calculated maneuver by the Taliban, according to preliminary U.S. military reports on the deadliest friendly fire incident with Pakistan since the Afghanistan war began.

The NATO airstrike killed 24 Pakistani soldiers over the weekend in an apparent case of mistaken identity, The Associated Press has learned.

A joint U.S.-Afghan patrol was attacked by the Taliban early Saturday morning. While pursuing the enemy in the poorly marked border area, the patrol seems to have mistaken one of the Pakistan troop outposts for a militant encampment and called in a NATO gunship and attack helicopters to open fire.

U.S. officials say the reports suggest the Taliban may have deliberately tried to provoke a cross-border firefight that would set back fragile partnerships between the U.S. and NATO forces and Pakistani soldiers at the ill-defined border. Officials described the records on condition of anonymity to discuss classified matters.

The incident has sent the perpetually difficult U.S.-Pakistan relationship into a tailspin.

Gen. James Mattis, head of U.S. Central Command, announced Monday he has appointed Brig. Gen. Stephen Clark, an Air Force special operations officer, to lead the probe of the incident.