The top U.S. military officer says he is comfortable that Pakistan's nuclear weapons are secure, but he says he is gravely concerned about Taliban advances in the country and neighboring Afghanistan.
Admiral Mike Mullen, the Chairman of the Joint Chiefs of Staff, says the United States has worked with the Pakistani military to improve the security of their nuclear arsenal. He says he believes the weapons will be kept out of the hands of terrorists.
"I remain comfortable that the nuclear weapons in Pakistan are secure," said Admiral Mullen. "That the Pakistani leadership and in particular the military is very focused on this. We, the United States, have invested fairly significantly over the last three years to work with them to improve that security and we are satisfied, very satisfied, with that progress."
Earlier, The New York Times reported that some U.S. officials are increasingly worried about the potential vulnerability of Pakistan's nuclear arsenal as the country faces a surge of militant activity. Citing unnamed officials, the report says there is U.S. concern about the potential for militants to snatch a weapon being transported or to insert sympathizers into laboratories or fuel-production facilities.
Mullen acknowledges there is a limit to what the United States knows about Pakistan's nuclear weapons, but he says Islamabad has made dramatic improvements in the arsenal's security in recent years.
"We all recognize, obviously, the worse downside with respect to Pakistan is that those nuclear weapons come under the control of terrorists," he said. "I do not think that is going to happen. I do not see that in anyway imminent whatsoever at this particular point in time. But it is a strategic concern that we all share."
Mullen says he is worried about recent military and political gains the Taliban and al-Qaida have made in Pakistan and southern Afghanistan.
"I am gravely concerned about the progress they have made in the south and inside Pakistan," said Mike Mullen. "The consequences of their success directly threaten our national interests in the region and our safety here at home. This is not about 'can do' anymore, this is about 'must do."
The Pakistan Army recently launched an offensive against the Taliban after militants entered the Buner district, 100 kilometers from Islamabad.
Admiral Mullen says it is too soon to tell whether those operations will have an impact over the long term.
"I am not trying to be judgmental in any way, shape or form, though I am following it very closely," he said. "Because I think the most important part of all this is, can these operations be sustained? And for Pakistan, not unlike other counterinsurgency efforts, there is a military piece of this. There is a clear piece of this. They are going through that now. But there also needs to be a hold and a build aspect of it."
Pakistan President Asif Ali Zardari and his Afghan counterpart, Hamid Karzai, are scheduled to meet in Washington this week with President Barack Obama.
The leaders are expected to discuss joint strategies to end violence and terrorism in their countries.