PESHAWAR, Pakistan (AP) — Militants in Afghanistan fired across the border at a Pakistani army post in a former local Taliban stronghold, killing two soldiers, the Pakistani military said Wednesday.

The cross-border firefight took place in the district of North Waziristan in the country’s northwestern Khyber Pakhtunkhwa province, the military said in a statement. It did not say when the attack occurred, but said Pakistani troops responded to the fire appropriately, without elaborating.

It was unclear whether there were any militant casualties. The military condemned the continued “use of Afghan soil for terrorist activities against" Pakistani troops, saying Pakistan had consistently asked Kabul to ensure effective border control on its side.

North Waziristan served as the headquarters of the Pakistani Taliban until the military secured it in 2015 with a series of operations. However, isolated militant attacks on troops and such cross-border violence have continued, raising fears the Pakistani Taliban were regrouping in the region bordering Afghanistan.

The Pakistani Taliban, also known as Tehreek-e-Taliban Pakistan, are a separate insurgent group from the Afghan Taliban, although Pakistan’s militant groups are often interlinked with those across the border.