By Nick Childs
BBC Pentagon correspondent
The top US commander in Afghanistan, Lt Gen David Barno, has said there has been a dramatic improvement in cross-border co-operation with Pakistan.
Taleban and al-Qaeda leaders are believed to move in the border area
The Pakistani military has stepped up its efforts in the search for remnants of al-Qaeda and the Taleban, he said.
It was the most detailed insight so far into the US' view of what is seen as a key element in the hunt for militants.
Al-Qaeda leader Osama Bin Laden and his followers are all thought to moving back and forth across that frontier.
'Hammer and anvil'
Local US commander Gen Barno, in a satellite link-up with the Pentagon, said the improvement had come over the last six to eight weeks.
The Pakistani military plus local paramilitary elements in the country's tribal areas have been undertaking a very serious effort, as he put it, working with the tribal leadership there to uncover and disrupt what he called terrorist organisations.
"We're moving in the direction of co-operative operations on both sides of the border - a hammer-and-anvil approach, if you will," he said.
Gen Barno said US and Afghan units would crush returning militants
"Al-Qaeda may be driven from the Pakistani side and we're ready to receive them on the Afghan side, use our forces in concert with Afghan forces on this side of the border to be able to, you know, crush the al-Qaeda elements between the Pakistani and the coalition forces."
Gen Barno also said his forces were re-energising their efforts and adjusting their tactics, as he put it, to search for the al-Qaeda and Taleban leadership.
The US military in Afghanistan has expressed confidence that it will find Bin Laden this year.
Gen Barno would not repeat that claim. There are no 100% certainties in the war-fighting business, he said.
But it seems that the improved contacts with and increased efforts by the Pakistani military are elements in the US military's renewed confidence.