Pakistan should work more closely with its neighbour Afghanistan in the fight against Taleban militants, US Secretary of State Condoleezza Rice has urged.
Ms Rice also raised the issue of democratic elections during talks
She praised both Pakistan and Afghanistan as great allies of the US, following talks with President Pervez Musharraf in Islamabad.
But she said the three nations needed "to unify all our efforts" to combat the threat of al-Qaeda and the Taleban.
Ms Rice will take the same message to Kabul, her next stop after Islamabad.
In recent months there has been a marked upsurge in Taleban-related attacks in Afghanistan, for which Kabul has often blamed Islamabad.
Ms Rice acknowledged the border between the two nations "is a difficult region".
"It has been a difficult region for a hundred years. It didn't start yesterday being a difficult region," she told a news conference after talks with President Musharraf.
"And so what we are all trying to do is to commit as strongly as we can to activities which make it ultimately impossible for al-Qaeda and Taleban to operate on that border.
"But our view is that we have two good friends and two fierce fighters in the war on terror."
Shortly before she arrived in Islamabad, Ms Rice told reporters: "The piece we need to work harder on is the co-operation that is US-Afghan-Pakistan in that region".
Pakistan told Ms Rice that it was deploying 10,000 extra troops to police the border with Afghanistan - on top of the 80,000 troops involved in fighting foreign and local militants in the tribal area.
Foreign Minister Khursheed Kasuri insisted Pakistan was doing what it could to tackle the insurgency. "Which country has a greater stake in peace and stability in Afghanistan?" he told reporters.
Tensions between Afghanistan and Pakistan have increased in recent weeks as violence, mostly in southern and eastern Afghan provinces, has soared.
Hundreds of people have been killed, including foreign troops, suspected militants and many civilians, in clashes and attacks this year.
Relations between the neighbours deteriorated sharply this year after fresh Afghan accusations that Taleban insurgents were able to operate from refuges in Pakistan.
Ms Rice will take up the issue with Afghan President Hamid Karzai during her brief stop in Kabul on Wednesday.
While in Islamabad, Ms Rice said she had also emphasised to President Musharraf the need to restore complete democracy in Pakistan by holding free and fair elections next year.