ISLAMABAD, Pakistan, June 29 -- The Pakistani military is at war with the Taliban, but the ambush that killed 16 soldiers in the tribal region of North Waziristan on Sunday was still somewhat unexpected.

"There is no operation which was either planned or being conducted in North Waziristan," Maj. Gen. Athar Abbas, a Pakistani military spokesman, told reporters Monday. "This attack was completely unprovoked."

The Taliban assault on an army convoy passing through the village of Inzar Kas was one of the deadliest incidents for the military during its two-month-old offensive against the insurgents. But to some analysts, it also served as a warning of a bigger threat -- the possibility that disparate Taliban factions might be closing ranks to battle the army in Pakistan.