The Pakistan-Afghanistan border remains the epicentre of the Al Qaeda [Images] activities, United States President Barack Obama [Images] has said, ruling out sending troops to Yemen where the group has become a concern of late.

"The border region between Afghanistan and Pakistan remains the epicentre of the Al Qaeda," Obama said in an interview to People magazine, the excerpts of which were released on Monday.

At the same time he acknowledged that the Al Qaeda's branch in Yemen has become 'a more serious problem,' but ruled out sending troops to Yemen at this point of time.

"I have no intention of sending US boots on the ground in these regions," Obama said. "I have every intention of working with our international partners in lawless areas around the globe to make sure that we're keeping the American people safe," Obama said.

US has currently deployed a large number of troops in Iraq and Afghanistan, with Obama saying the war's focus is the latter country. The number of US soldiers in Afghanistan is set to cross the 100,000 mark.

Al Qaeda's activities in Yemen came to prominence following the failed attempt to bomb a US plane by a Nigerian national, whose responsibility was later claimed by the Al Qaeda in Arabian Peninsula, which has its base in Yemen.

The President's words were echoed by his top military generals too and the CENTCOM Commander General David Petraeus, told CNN that Af-Pak, not Yemen, remains the most important location for the war against the Al Qaeda.

"I don't think it (Yemen) is the most important (location for the war against Al Qaeda)," Petraeus said.

"That would likely still be the western Pakistan, Afghanistan border area, but certainly a very important area, in an area where, again, it has been resurgent... Somalia another one like that, at a time when the Al Qaeda has suffered severe reverses in Saudi Arabia, been reduced considerably in Iraq, and indeed, even in the western areas of Pakistan, Afghanistan," he said.

Ruling out the prospect of sending troops to Yemen, he said, "We would always want a host nation to deal with a problem itself. We want to help. We're providing assistance."

The US asked the Yemen government to crack down on the Al Qaeda network and pledged assistance following the failed Christmas Day attack.

"So we're going to provide more assistance in the course of this year than we did last year," Petraeus said. Noting that Yemen is a sovereign country, Admiral Mike Mullen [Images], Chairman Joint Chiefs of Staff, said, "We have great respect for the President there in terms of his judgement, in terms of what he needs to do this."

"Right now, as far as any kind of boots on the ground there with respect to the US, that's not a possibility... We're not into those kinds of discussions," he added. Mullen told CNN that given the relatively small but 'agile, very capable, cunning' militants who have 'studied us' were active against the US, it does take 'larger numbers to get at those' and added the Al Qaeda threat 'is not going away.'

"This Al Qaeda threat is not going away. It's going to keep coming at us and I don't just mean us, the United States, I think us, internationally -- until we take steps to finish it off," Mullen said.

Republican Senator John McCain [Images] said the Al Qaeda continues to inhabit areas along the Afghan-Pakistan border which argues for success in Afghanistan.

"But I think that we have to continue our emphasis and our focus on the fact that this challenge is not going away any time soon," he told the CNN.