Pakistani troops have launched an operation against suspected al-Qaeda fighters in the tribal region bordering Afghanistan, officials say.
The army believes hundreds of foreign militants are in the area
Helicopter gunships and artillery have been used to bomb locations near Wana in South Waziristan to flush out suspected militants.
The army says six militants and two soldiers have been killed.
The offensive began as US Deputy Secretary of State Richard Armitage held talks in Islamabad.
A spokesman for the militants in Waziristan confirmed the death of two of their men in the fighting.
The army opened an artillery barrage at first light on Tuesday targeting a mountainous area east of the town of Wana.
Helicopter gunships supported the bombardment.
The BBC's Haroon Rashid in Peshawar says that all roads leading to the area have been sealed.
A local resident said government forces appeared to be concentrating their attack in an area that is a stronghold of Abdullah Mehsud, a Pakistani militant whose men kidnapped two Chinese engineers last month.
'Enhancing US-Pakistan relations'
In the Pakistani capital, Islamabad, Richard Armitage met President Pervez Musharraf and Foreign Minister Khurshid
Kasuri for talks on a wide range of issues, including the war against terrorism.
Armitage's visit follows soon after President Bush's re-election
Mr Armitage is the first senior US official to visit Pakistan since President Bush was re-elected and he promised continuity of US policies in the region.
"We certainly want to continue our excellent cooperation with the military," Mr Armitage told Pakistani television, adding that economic ties needed to be strengthened.
He also thanked Pakistan for helping with Afghanistan's presidential election on 9 October.
Foreign Secretary Riaz Khokhar, who also met Mr Armitage, conveyed, Pakistan's desire to promote "a solid, broad-based and long-term relationship with the US encompassing cooperation in areas of investment, trade and defence," Pakistan's foreign ministry said.
Mr Armitage is being accompanied by US Assistant Secretary of State for South Asia, Christina Rocca.
He is also due to visit India and Afghanistan.
Pakistan has been closely cooperating with US forces in the hunt for al-Qaeda militants and remnants of Afghanistan's former Taleban regime.
Since March, tens of thousands of Pakistani troops have been deployed along the tribal belt bordering Afghanistan, to flush out foreign militants believed to be linked to al-Qaeda.
Nearly 600 al-Qaeda suspects have been caught and handed over to US forces.
Last month, a videotape of Osama bin Laden was delivered to the Islamabad bureau of the Arabic television channel, Al-Jazeera, a development that correspondents say deeply embarrassed the Pakistani administration.