Early Thursday, a pair of gunmen on a motorbike killed a soldier and a high-ranking army officer in the Pakistani capital, Islamabad, police said.
The attack appeared to be part of a wave of bloodshed that has killed more than 170 people in Pakistan over the past three weeks, pressuring the military to launch the offensive in South Waziristan six days ago.
The offensive is considered a critical test of nuclear-armed Pakistan's campaign against Islamist extremists who also are blamed for attacks on Western forces in neighboring Afghanistan.
The military is advancing on multiple fronts in South Waziristan, a tribal region home to al-Qaida fighters and Taliban insurgents who have focused on overthrowing the U.S.-allied Pakistani government.
The fight for the town of Kotkai is symbolically important because Pakistani Taliban chief Hakimullah Mehsud and a top deputy, Qari Hussain, hail from there. Kotkai also lies on the way to the major militant base of Sararogha.