Amidst concerns that Pakistan's nuclear arsenal may fall into the hands of fundamentalists, the US has said that Islamabad's atomic weapons are safe.

"We feel pretty comfortable at this moment of time. And of course we'll pay attention to any country that has got nuclear weapons," US President George W Bush [Images] told ABC News when asked about the safety of Pakistan's nuclear weapons.

Bush's view comes hours after a top Pentagon official said that there is no "problem" linked to the security of Pakistan's nuclear weapons.

"I've been asked previously about the security of the nuclear weapons. I see no indication that that's a problem," Chairman of the Joint Chiefs of Staff Admiral Mike Mullen said at a briefing held at the Washington Foreign Press Centre.

Admiral Mullen was asked to look at the worst case scenario in Pakistan where the nuclear weapons fell into the wrong hands and if Washington had any options.

"I try not to spend much time speculating on what-ifs. But certainly, part of the understanding of where we are with respect to those weapons is ensuring that they are secure, and being mindful and watchful of that," Admiral Mullen said.

He stressed that there has been no "significant effect" on the military-to-military contacts between Washington and Islamabad due to the emergency there.

"From a military standpoint, I haven't seen a significant effect," the top military official said in response to a query on the impact of the Pakistan emergency on the US mission in Afghanistan.

We continue the contacts. And so, from that standpoint, the logistics support, in terms of what goes through Pakistan to support our efforts in Afghanistan. We have seen no interruptions there as well. So, from that standpoint, we just haven't seen much," Admiral Mullen pointed out.

Chairman of US Joint Chiefs of Staff said: "On a larger scale, or at a higher level, one of the challenges that we have globally is to control weapons of mass destruction, and that we all need to work together to do that.

"And I think that will continue to be a huge challenge," Admiral Mullen said.

"So, to have a weapon -- a nuclear weapon that in the hands of a terrorist anywhere in the world be a huge, huge challenge for all of us," the top US military official said.

Meanwhile, Bush described Pakistan President Pervez Musharraf [Images] as "a man of his word" and expressed confidence that the military ruler will follow his advice to end emergency.

"He (Musharraf) made a decision, we did not necessarily agree with his decision, to impose emergency rule, and hopefully he will get rid of the rule," Bush said.

"He (Musharraf) truly is somebody who believes in democracy. He has done more for democracy in Pakistan than, any modern leader has," the US president said.

A "strong" US ally in the war on terrorism in Afghanistan since September 11, Musharraf declared emergency in Pakistan on November 3 citing spur in militancy and judicial intervention in day-to-day affairs of the country.