Pakistan, the world’s only nuclear-armed Islamic nation, has been engulfed in a wave of political and religious unrest. Could Muslim extremists take control of Pakistan’s nukes?

How big is Pakistan’s nuclear arsenal?
Big enough to threaten the planet, if the weapons fall into the wrong hands. Pakistan has at least 50 and as many as 120 nuclear warheads, according to U.S. intelligence sources. It also possesses missiles capable of reaching neighboring India, Iran, and Afghanistan—and possibly more distant targets. The nuclear material in most of the warheads is highly enriched uranium, which is relatively easy to produce but also very heavy—too heavy for many of Pakistan’s missiles to carry. But Pakistan is also reprocessing spent nuclear fuel into plutonium, which is much lighter than enriched uranium and which produces bombs that are both more compact and more powerful. In 2006, Western intelligence satellites revealed that Pakistan was building a reactor capable of producing enough plutonium to fuel 40 to 50 new bombs a year.

Where are the weapons stored?
Outsiders, including the U.S., don’t really know for sure. It is known that Pakistan stores nuclear weapons and components in bunkers scattered around the country, including along the volatile border area with Afghanistan. Pakistani authorities have also indicated that some warheads are maintained near the border Pakistan shares with India, its longtime adversary. But Pakistan jealously guards the exact locations of the bunkers, to deter any terrorist plots, as well as to stave off pre-emptive attacks by any enemies. “This is an extremely sensitive matter in Pakistan,” said President Pervez Musharraf. “We don’t allow any foreign intrusion in our facilities.”

Why does Pakistan have nukes?
Because India has them. Pakistan and India have been bitter rivals since 1947, when colonial India was partitioned into the two independent countries. In 1974, India conducted its first nuclear test, setting off a desperate scramble in Pakistan to develop its own nuclear capability. In 1998, India exploded a nuclear weapon underground, erasing any doubt of its nuclear capability. Pakistan quickly countered with five underground tests of its own. “If India wants to prove its manhood by conducting a nuclear test, then we have the capability to prove our manhood,” said Foreign Minister Sardar Asif Ahmed Ali. Pakistanis celebrated their nuclear program as “a triumph for Islam.”

How was Pakistan able to develop a bomb?
Through subterfuge and espionage. Following India’s 1974 test, then–Prime Minister Zulfikar Ali Bhutto (father of the recently assassinated Benazir) tapped Dr. Abdul Qadeer Khan, a talented, ambitious metallurgist, to head the country’s nuclear-development program. At the time, Khan was working in the Netherlands for the European research consortium Urenco, where he had access to state-of-the-art nuclear technology, including blueprints for the centrifuges that spin raw uranium into nuclear fuel. He stole the designs and smuggled them back to Pakistan, and then set up a nuclear research facility in Kahuta, near Islamabad. To deflect suspicion, he ordered parts from many companies, often using middlemen to disguise their ultimate destination. He also became notoriously corrupt, pocketing millions as he sold nuclear technology on the international black market.

Does the U.S. help protect the weapons?
It does what it can. Since the 9/11 attacks, the U.S. has spent about $100 million training and equipping Pakistan’s nuclear-security personnel and building a nuclear-security training center in Pakistan. But Pakistan’s military leaders are reluctant to cooperate too much with the U.S., suspecting that the aid is a ruse to learn the location of Pakistan’s weapons. Likewise, many in the U.S. intelligence establishment object to sharing too much American expertise, out of concern over revealing too much about U.S. weapons. This frustrates many nuclear experts outside government, who say the Pakistanis would greatly benefit from more U.S. input into how to prevent accidental or malicious detonation of nukes. “We should share this technology,” says Harold Agnew, former director of the Los Alamos weapons laboratory. “Anybody who joins the [nuclear] club should be helped to get this.”

Are the nukes secure?
The U.S. believes they are—at least for now. “I don’t see any indication right now that security of those weapons is in jeopardy,” said Joint Chiefs of Staff Chairman Adm. Mike Mullen. “But clearly we are very watchful.” A Pakistani general involved in nuclear security, interviewed recently in The Philadelphia Inquirer, described a multilayered system of safeguards for weapons. Warheads, he said, are stored separately from missiles, and several government and military officials must provide authorization for a launch, so no one individual could start a war. “Pakistan’s nuclear weapons are absolutely safe and secure, irrespective of the political situation,” the unnamed general said. But U.S. officials have expressed concern that rogue government elements with jihadist sympathies could provide nuclear expertise, if not material, to the extremists. It’s not a far-fetched concern. In 2001, Pakistan arrested two retired nuclear scientists after they allegedly met with Osama bin Laden and offered to help him build a bomb. “I am confident of two things,” said former CIA Deputy Director John McLaughlin. “That the Pakistanis are very serious about securing this material, but also that someone in Pakistan is very intent on getting their hands on it.”