A suicide bomber has killed at least four soldiers in north-west Pakistan near the Afghan border, officials said.
The bomber drove a car laden with explosives into a military convoy near Miranshah, the main town in the North Waziristan tribal area.
Several others were injured in the attack. A military vehicle was also severely damaged, officials said.
The US says North Waziristan is a safe haven for the Taleban and al-Qaeda. Pakistan denies the claim.
Troops were rushed from Miranshah to the scene after Friday morning's attack, officials said.
Violence has soared in North Waziristan and other areas along the border since troops stormed the radical Red Mosque in the capital, Islamabad, in July, with the deaths of more than 100 people.
More than 200 people have been killed in violence since then. Pro-Taleban militants ended a controversial truce with the government in protest at the attack on the mosque.