A bombing claimed by the Pakistani Taliban has killed at least 20 Pakistani soldiers and wounded 30 others.
The explosion on Sunday ripped through a military convoy as it prepared to leave the town of Bannu to go to the North Waziristan tribal region, a stronghold for al-Qaida-linked militants.
Officials of Pakistan's army said the bomb was planted in a civilian vehicle that had been rented locally to transport the troops. The army says it frequently hires vehicles from the local population.
The Tehreek-e-Taliban claimed responsibility for the attack. A spokesman said the group will "carry out more such attacks in the future."
Pakistan's Prime Minister Nawaz Sharif condemned the bombing and canceled his trip to this week's World Economic Forum in Davos, Switzerland.
The Taliban has conducted a bloody insurgency against the Pakistani state since 2007. The bombing Sunday was the biggest against Pakistani security forces in months.