"The student body has become very conservative, very Islamist, their outward appearance has changed," says Professor Hoodbhoy, the chair of the physics department at Quaid-i-Azam University in Islamabad. "It's row after row of these burqa women."
Students avoid talking politics with Hoodbhoy, a cautionary voice on nuclear weapons in a nation that takes boisterous pride in having them. "They think I'm on the wrong side," he says.
International concerns are mounting again about the security of Pakistan's nuclear weapons as fighting rages with the Taliban. But thanks to safeguards, experts worry much less about the Islamic fighters in the hills making off with a warhead. It's the radicals among the educated – potential insiders – who are in a more realistic position to abscond with nuclear material and know how to use it.
"Nuclear weapons are just about as safe as the people who are their custodians," says Hoodbhoy. The threat comes not from the "mountain barbarians," he says, but from "Al Qaeda, together with their Islamist allies within the Pakistani state and society. These are urban people, engineers, technicians, people in fairly high offices."
Clinton worries about Taliban getting A-bomb
According to research compiled by the Federation of Atomic Scientists, Pakistan has several suspected nuclear facilities near regions with Taliban infiltration. Media reports that the Taliban fighters had moved within 100 kilometers (62 miles) of the capital prompted the latest concern.
"One of our concerns is that if the worst, the unthinkable were to happen, and this advancing Taliban were to essentially topple the government ... then they would have the keys to the nuclear arsenal of Pakistan," said US Secretary of State Hillary Rodham Clinton late last month.
But the notion of the Taliban as a conventional force able to overrun such sites overlooks the massive size of the Pakistani military, centered on the twin cities of Islamabad and Rawalpindi, near where much of the nuclear infrastructure also lies.
After a week of requests, Pakistani military officials failed to offer comment on their program's safeguards. But Pakistan has assured the West that certain procedures are in place. These include keeping warheads in a disassembled state, requiring multiple people to sign off on any activation orders, and so-called permissive action links that electronically lock the warheads unless codes are provided and environmental conditions – such as atmospheric pressure for plane-dropped bombs – are met.
$100 million US investment in nuke security
The US also spent $100 million to help Pakistan beef up nuclear security. Several experts said it's unknown exactly how that money was spent, but presumably it went toward these safeguards, enhancing perimeter fencing, and advanced training of personnel.
"It was money well spent," says Rolf Mowatt-Larssen, who was the head of nuclear intelligence at the US Department of Energy until January. "There's not a lot of transparency into it though, and going into it I think the US felt like that was acceptable."
Presuming Pakistan has indeed implemented the safeguards it says it has, experts say the chance of outsiders snatching a usable warhead is extremely small.
"It would be very hard for pure outsiders to take over a facility," says Mr. Mowatt-Larssen. "My big concern is the insider threat combined with outsiders."
Specifically, insiders could pass nuclear material to the outside as it passes through multiple production facilities. Most of Pakistan's estimated 60 to 100 warheads are made from highly enriched uranium. That involves moving uranium from a mine to several processing plants before producing a grapefruit-sized core of a nuclear bomb.
Three years to build a bomb from scratch
Hoodbhoy estimates it would take one of his physics graduate students about three years to figure out how to take that material and build a crude bomb from scratch on the magnitude of Hiroshima.
Further, if material gets pilfered, there's no guarantee anyone will notice. The theft of a warhead remains hypothetical, but there have been cases of stolen nuclear material showing up on the black market. In all of those cases, the facility where it came from never noticed it went missing, says Mowatt-Larssen.
For this reason, he talked to then-Pakistani President Pervez Musharraf about sending someone to the country's nuclear facilities to do an in-person audit of materials – a suggestion Mowatt-Larssen says was taken seriously.
Pakistan's credibility on nuclear security took a nose dive following revelations in 2004 that scientist A.Q. Khan sold materials and know-how to states like North Korea. However, it's unclear whether to view Mr. Khan's activities as a true security breach, or merely the conducting of state business.
The country now has a quarter-century track record, point out some experts, and it's one that suggests the most serious risk isn't unique to Pakistan.
"The only scenario that gives me concern is one that applies as much to the US as Pakistan, which is the question of accidents occurring," says Shuja Nawaz, an analyst at the Atlantic Council in Washington, D.C. In fact, it's the United States that recently transported a live nuke across the country by accident, while there have been no reports of such mishaps in Pakistan or India. But "even with the best-laid plans, things happen."
As for the risk of rogue insiders, Mr. Nawaz says American technical assistance as well as periodic monitoring of personnel help mitigate the potential.
As teacher to some of the people in Pakistan's program, Hoodbhoy has one window into the personnel risk. He recalls one PhD candidate who was "very right wing" and went on to a top military position. "After spending a few years with me, I think some of his edges came off," he says.
No love for Taliban
On the lawn in front of the university library, 10 of Hoodbhoy's physics graduate students are cramming for a test together and enjoying the sunshine. The consensus among them is pride in Pakistan's nuclear weapons program, but there's little indication they have any affinity for radical Islam.
They speak of being disgusted with the Taliban and are supportive of the military action to crush them, a view shared by students from Taliban-influenced regions of the North West Frontier Province (NWFP) and Swat Valley.
"They do this by guns and they don't want peace. They just want to impose on us, and we are with the Army," says Madiha Maryam from Rawalpindi. She has her hair covered by a scarf, something she says doesn't mean she's conservative: "I like wearing the scarf and everyone should do what they like."
From behind full face covering, Nilem Khaliq from the NWFP says, "of course we are proud" of Pakistan's nuclear arsenal. Yet, if she could choose, "we want all nuclear weapons to be restricted for all countries in the world" – not just Pakistan.