ISLAMABAD: A raid by militants on a Pakistani naval base this week has raised fresh anxiety about Pakistan's ability to protect its nuclear sites. Although Western governments and analysts agree there is little chance militants could succeed in stealing nuclear material in an assault like the one in Karachi, attacks by al Qaeda or the Taliban against a nuclear facility remain a possibility.
A serious breach of the security perimeter could lead to calls for a unilateral American move to secure the Muslim world's only nuclear weapons, something that likely would trigger massive protests inside Pakistan and more hostility between Washington and Islamabad - an outcome that would be welcomed by the militants.
While that is unlikely, a scenario that includes more militant attacks on Pakistani security force installations in the coming weeks, possibly nuclear ones, is not. That alone could deepen the worry in the United States that the Pakistani army is infiltrated by militants and is unable to protect the weapons.
"These attacks alone do not damage the military, but they shape American fears," said Kamran Bokhari, a Pakistan expert from Stratfor, a global intelligence firm. "More attacks create the perception that the Pakistan state is crumbling and weakening, and that encourages more American unilateral operations, and that serves the jihadists' interest."
Pakistan is thought to have around 100 nuclear weapons around the country, but that number is growing each year.
The army believes they are the country's main safeguard against Indian aggression, and ensures they are protected to a standard comparable to other countries weapons, according to analysts and research papers. They are held in bases with much tighter security than the Mehran Naval Station attacked on Sunday in Karachi, in bunkers protected by specially trained security forces.
The army physically separates warhead cores from their detonation components, while the warheads themselves are electronically locked to ensure that they cannot be detonated even if they fall into terrorists' hands.
The Mehran facility is on the grounds of a large air base that has housing complexes and a hospital and borders large residential and commercial areas. Nuclear facilities are isolated and access to them is much more strictly controlled.
While the fear that the weapons may be snatched in a militant raid is considered overstated, a more pressing concern is that the inherently unstable Pakistani government could be ousted by Islamist extremists - and the new dynamics that would bring, including state-sanctioned nuclear proliferation to other countries or militant groups.
The fact that Osama bin Laden was killed by American commandos on May 2 in an army town a short walk from a top military academy has added to concerns that elements within the security forces, the most powerful institution in Pakistan, are sympathetic to al Qaeda.
"Some observers fear radical takeover of a government that possesses a nuclear bomb, or proliferation by radical sympathizers within Pakistanis nuclear complex in case of a breakdown of controls," said a 2011 US Congressional report on the country's nuclear weapons. "While US and Pakistani officials continue to express confidence in controls over Pakistan's nuclear weapons, continued instability in the country could impact these safeguards."
During a news conference Tuesday in Kabul, NATO Secretary General Anders Fogh Rasmussen acknowledged the ongoing concerns about the safety of Pakistan's nuclear weapons, but said he "felt confident that Pakistan's nuclear arsenal is safe and well-protected."
"But of course," he added, "it is a matter of concern and we follow the situation closely."
The 18-hour assault on the base was one of the most successful militant strikes in over four years of insurgent violence, foreshadowing what many here fear is going to be a long and bloody summer as militants seek to exploit tensions between Pakistan and the United States exposed by the unilateral US raid against the al Qaeda leader. The Pakistani military, already humiliated by not knowing about the existence of bin Laden in Abbottabad and being unable to detect the U.S. choppers flying into the country, was again shown during the Karachi attack to be powerless, this time against a domestic threat that for first time destroyed two of its planes.
Each Taliban statement claiming responsibility for revenge strikes since the killing of bin Laden has singled out the army for criticism for failing to stop the American action. In doing so, the militants are trying to align themselves with public sentiment and show that they are the best force to protect the country, even as they kill innocents in bombings.
Few expect any answers on how the attackers got into the complex in Pakistan's largest city, much less the trial of anyone arrested in connection with it. A 2009 attack on army headquarters close to the capital Islamabad was led by a former army nurse who was arrested at the scene. The man, whose name has not been released, has been held without trial since then, and the results of any investigation into that attack have never been public.
There were already discrepancies emerging over the number of attackers in Karachi. An initial investigation report compiled by police on Tuesday stated that there were 12 assailants, double the number declared by the government and the navy on Monday.
Navy chief Admiral Noman Bashir said two of those attackers who escaped were "facilitators who brought in equipment and ammunition for their accomplices," but gave no more details.