Pakistani officials say the military has launched an offensive in the Kurram tribal district near the Afghan border.
Officials say the operation is aimed at removing a Pakistani militant group called Tehrik-e-Taliban Pakistan, which is believed to be active in the area.
Brigadier Azmat Ali, a senior officer of the Pakistani Army's media wing, told RFE/RL's Radio Mashaal.
"It has started in some areas and will be launched in some other areas. This is not a very big operation. The offensive is like the one conducted in [Pakistan's] Malakand [district]. This operation is meant to remove pockets [of militants]," Ali said.
Security officials say the increase in violence has reportedly caused thousands of families to flee the area.
Kurram Valley is located along the porous Afghan-Pakistan border, which is rife with insurgent activity and often serves as a haven for militants fleeing either country.