The top US military officer, Admiral Mike Mullen, held talks with Pakistani leaders on Wednesday aiming to patch up ties strained by a flurry of US strikes against militants in Pakistan.
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.
US officials say Taliban and al Qaeda-linked fighters use ethnic Pashtun tribal regions on the Pakistani side of the border as a springboard for attacks into Afghanistan.
A new government in nuclear-armed Pakistan has committed itself to the US-led campaign against Islamist militancy even though support for the United States is deeply unpopular.
But Islamabad objects to cross-border strikes and protested against a bloody helicopter-borne ground assault by US commandos in South Waziristan this month. There have been five US missile strikes this month, killing militants and civilians.
Dealers said the Pakistani rupee weakened to a record low of 77.20/30 to the dollar on Wednesday partly because of tension with the United States, a major source of financial help for Pakistan as it struggles with economic problems.
A US embassy spokesman said Mullen wanted to improve coordination and cooperation with the Pakistani military.
"Admiral Mullen has worked to forge a closer relationship and he wants to continue the relationship building," said the spokesman, Lou Fintor.
Pakistan's army commander, General Ashfaq Kayani, said last week Pakistan's territory would be defended at all cost and a military spokesman said on Tuesday aggression across the border would be confronted.
Asked about Pakistani anger over cross-border US strikes, Fintor said Mullen "recognised the concerns expressed by General Kayani and desires to continue the dialogue".
"The United States is committed to working with Pakistan to eliminate the safe havens," he said.
Mullen met Kayani and was due to see Prime Minister Yousaf Raza Gilani and other officials.
US President George W Bush approved the US commando assault in South Waziristan on Sept. 3 without Islamabad's permission as part of a presidential order on covert operations, officials and sources familiar with the matter said.
But officials and analysts in Washington said the Bush administration was unlikely to use commando raids as a common tactic against militant havens in Pakistan because of the high-stake risks to US policy in the region.
Any future raids must be approved on a mission-by-mission basis by a top US administration official because of the political sensitivities involved and the calculated risk of US troops being killed or captured on Pakistani soil, they said.
"This is extremely sensitive. You can't have soldiers in the field, or even their commanders, making this kind of decision," said one official, who spoke on condition of anonymity because the topic involves classified information.
Pakistani security officials said on Monday firing by Pakistani troops forced two US military helicopters to turn back to Afghanistan after they crossed into Pakistani territory, although the US and Pakistani militaries denied it.
Pakistan's new president, Asif Ali Zardari, said in London on Tuesday he did not believe the United States would carry out more raids.
There have been no reports of anyone killed by US incursions or missiles since Friday but pilotless drones have been prowling over militant sanctuaries on the Afghan border.
Villagers in both South and North Waziristan said drones were flying on Tuesday night. An intelligence official said a drone fired a missile after militants tried to shoot it down with an anti-aircraft gun. No casualties or damage were reported.