ISLAMABAD – Pakistan said Friday four of its soldiers were killed when “terrorists” raided a security post in a remote northwestern district.

The overnight attack occurred in South Waziristan, near the border with Afghanistan, an army statement said.

Pakistani troops responded promptly and killed four assailants, it added.

No one immediately took responsibility for the attack.

The district is a known former stronghold of the Tehrik-e-Taliban Pakistan, an alliance of outlawed extremist groups. TTP is also known as the Pakistani Taliban.

Pakistani officials say sustained military-led operations in recent years have cleared Waziristan and surrounding districts of militants, aside from isolated pockets.

The security operations have killed thousands of militants and forced others to take refuge in volatile Afghan border districts.

The United Nations said in a recent report that TTP has regrouped in Afghanistan and gained strength.

The TTP has “overseen a reunification of splinter groups that took place in Afghanistan and was moderated by Al-Qaida,” according to the 27th U.N. Analytical and Monitoring Team report of Feb. 3.

“One member state reported that TTP was responsible for more than 100 cross-border attacks between July and October 2020,” it said.