NEW YORK, Nov 15: As the Taliban forces fled major Afghan cities, US Defence Secretary Donald Rumsfeld said that America’s number one enemy Osama bin Laden might even have access to a helicopter and might try to sneak out of Afghanistan to rendezvous with a waiting jet in a nearby country.

“My guess is what he’d probably do is take a helicopter down one of those valleys that we couldn’t pick up and pop over to some part of the country where there is an airfield and have a plane waiting for him,” Rumsfeld told the New York Times in an interview.

As the American military campaign shifts to the South, the operation has entered a far more complex phase. Mr Rumsfeld sent a double-barrelled message.

He indicated that the American military would keep up the pressure during Ramadan by continuing air strikes. At the same time, he counselled patience for a strategy that depends on proxy forces, air power and commandos but not substantial numbers of American ground troops, the Times said.

His remarks came as the emphasis of the American-led military campaign was changing from the bombing of Taliban troops to the hunt for enemy leaders.

“I suspect you’ll find people just fading into the countryside within Afghanistan,” Mr Rumsfeld said. “There’s no question that the people will be moving out. They’ve been doing this for centuries.”

The Times said that in recent weeks, some critics have said that the Bush administration has been fighting with one hand behind its back by refraining from sending in substantial numbers of American ground troops. That, they assert, has minimized the risk of American casualties while increasing the chances that Osama might escape.

In his interview, Mr Rumsfeld seemed to be at pains to rebut this argument by pointing to the role of the United States Special Operations forces in the South.

Mr Rumsfeld indicated that one of the missions was setting up checkpoints along roads in the South in the hope of catching Taliban and al-Qaeda commanders. He did not say if any had been killed but indicated later that none had been captured.

“They are letting the population know that everyone best be careful what they do, where they go, how they behave, and that there’s a presence in the South that had not been there previously,” Mr Rumsfeld added.

He told the Times, however, that it might be possible for Osama to flee Afghanistan.

“He’s got the wherewithal to do pretty much what he wants, at least to try to,” Mr Rumsfeld said.

He said that three-quarters of the Taliban’s fleet of helicopters has been destroyed. But he said some may have been hidden and available to Osama. Detecting helicopters after they are aloft, he said, could be difficult if they hugged the ground and operated in bad weather. “I’ve heard reports that helicopters have been observed in and around the Pakistani border in weeks past that we were not able to detect,” Mr Rumsfeld said.

Still, he voiced hope that Afghans would help the US find Osama and his men, motivated in part by the huge reward the administration is offering. “We’re actively trying to make it hard for him to do anything,” he said. “And we spend a lot of time looking for the leadership cells of al-Qaeda and Taliban, and when we find them we try to destroy them.”