The US on Thursday said Pakistan's nuclear stockpile was not 'endangered' following a daring terrorist attack on the key Kamra Air Force base, believed to house atomic weapons.

"I do not have any indication that this particular attack (Kamra) has endangered the Pakistani nuclear stockpile," Pentagon Press Secretary George Little told reporters during an off camera news conference.

He was responding to news reports coming from Pakistan that the attack on the military base in Kamra had threatened the safety of Pakistan's nuclear weapons.

"As for the safety of the Pakistani nuclear programmes, we obviously work closely and on regular basis with Pakistani counterparts towards the safety of their nuclear programme. It is our sense that the Pakistani government maintains good security around their nuclear arsenal," Little said.

The Pakistani Taliban has claimed the responsibility of the attack that left nine attackers and a soldier dead and parts of the complex ablaze. But Pentagon maintained that it has no information on this. "I can't confirm attribution for this particular attack. Obviously we are concerned and saddened by this attack," Little said.

Early this week, US Defense Secretary Leon Panetta had expressed concern that Pakistan's nuclear weapons might land in the hands of terrorist outfits if terrorism inside the country is not brought under control.

"We have confidence that the government of Pakistan is well aware of the range of potential threats to its nuclear arsenal and has secured its nuclear arsenal accordingly. We do talk about these issues and support Pakistani efforts to keep them secure; we have for quite a long, long time. And you know, we don't have any reason to be concerned at this moment," State Department spokesperson Victoria Nuland told reporters.

Nuland was responding to questions on the safety of the Pakistan's nuclear arsenal in the wake of the terrorist attack on the military base.

"Pakistan itself has issued a statement in the last couple of hours denying that there was either any nuclear material or any nukes at this site, and we don't have any information that would contradict that," she said.

The State Department official expressed her condolences over the death of people due to the terrorist attack. "We express our condolences for the loss of life suffered by the Pakistani military again at the hands of terrorists. As you know, Pakistanis have suffered more than their share at the hands of terrorists inside Pakistan, which speaks to our efforts to address this threat together and to try to address it as a community operating in that region," Nuland said.

"We have been working well with Pakistan in trying to look again at what we can do now that the GLOCs are open to strengthen our counterterrorism rhythm and cooperation. We have seen improvement in recent weeks in the cooperation we are having, Afghanistan, Pakistan and ISAF, trying to squeeze these networks," she said.

"It is not unusual that when they feel squeezed, they lash out. But that just speaks to the necessity of continuing our efforts to end their ability to exact violence on Pakistani citizens or any of us," Nuland said.