Pakistani aircraft bombed militant strongholds in a northwestern region on Tuesday while US drones prowled the sky over another militant sanctuary on the Afghan border, a military official and residents said.

Pakistani forces launched offensives against al Qaeda and Taliban militants in the northwest in August and the government says hundreds of militants have been killed.

But at the same time, US forces have stepped up strikes on militants on the Pakistani side of the border, angering Islamabad and straining relations between the allies.

Admiral Mike Mullen, chairman of the US Joint Chiefs of Staff, was due in Pakistan late on Tuesday.

Mullen said this month he was not convinced Western forces were winning in Afghanistan and he was looking at a new, more comprehensive strategy that would cover both sides of the border, including Pakistan’s tribal areas.

Pakistani aircraft bombed three areas of Bajaur on Tuesday as ground troops searched house-to-house for militants, a military spokesman said.

They have constructed underground bunkers and along with foreign fighters are putting up stiff resistance. Troops are clearing each and every house in these areas, said military spokesman Major Murad Khan.