Including shoulder-fired heat-seeking missiles that could be used by terrorists to shoot down civilian airliners.

The sign on the wall reads “Schoolbook Printing and Storage Warehouse,” but the fact that the double gates in the wall have been crudely ripped off suggests that something more interesting might be inside.

It turns out that the only books to be found in any of the three large buildings in the walled compound are manuals how to fire rocket launchers and wire-guided missiles, among others. The buildings are actually disguised warehouses full of munitions mortar shells, artillery rounds, antitank missiles and more — thousands of pieces of military ordnance that are completely unguarded more than two weeks after the fall of the capital.

Perhaps most interesting of all is what is no longer there, but until recent days apparently was: shoulder-fired heat-seeking missiles of the type that could be used by terrorists to shoot down civilian airliners. U.S. authorities have long been concerned that Libyan missiles could easily find their way onto the black market.

These missiles, mostly SA-7b Grails, as NATO refers to them, have been spotted in Libya before and are well known to have been sold to the government of Muammar Qadhafi by former Eastern bloc countries. The evidence at the schoolbook warehouse confirms just how large those quantities were. It also raises questions about how many of them may have been purloined by rebels, criminals or smugglers.

Matthew Schroeder, who researches heat-seeking antiaircraft missiles and their proliferation for the Federation of American Scientists in Washington, said that the discovery of yet another looted arms depot in Libya was cause for concern, especially depots that contained what security specialists call Man-Portable Air-Defense Systems, or Manpads.

Western governments and nongovernment organisations have repeatedly asked and prodded the rebel government, the National Transitional Council, to secure the vast stockpiles of arms that it has inherited, apparently to little avail.

“Claims that depots holding Manpads and other dangerous weapons are still not being properly secured are very worrisome and should be thoroughly investigated,” Mr. Schroeder said. “In cases where stockpile security is found to be lacking, immediate steps should be taken to correct any deficiencies.”

In Washington, President Barack Obama's top counterterrorism official, John O. Brennan, said that the spread of shoulder-fired missiles and other weapons from Libya's arsenal posed “a lot of concerns,” and that the United States had pressed the rebel government to secure weapons stockpiles.

“Obviously, there are a lot of parts of that country right now that are ungoverned,” he said at a security conference.

A senior U.S. military officer who follows Libya closely said it was puzzling that there had been so few documented instances in which Libyan loyalist troops launched shoulder-fired missiles at NATO aircraft.

“I'm not sure what that means,” the officer said. “Fewer systems than we thought? Systems are inoperable? Few in Libya know how to operate them?”

The officer said it was also unclear whether the al-Qaeda or other extremist groups had acquired the missiles, although he said intelligence analysts were assuming they had.

“But if they do, why haven't they used or threatened to use?” the officer said. “It's all very murky right now.”

Wednesday, a reporter for The New York Times as well as a researcher for Human Rights Watch and other reporters who visited the scene found 10 crates that had held two missiles each lying opened and empty. The crates were clearly labelled as coming from Russia.

“Other countries know these weapons are on the loose, and they will be trying to get their hands on them,” said a researcher for Human Rights Watch, Peter Bouckaert.

He was particularly concerned with one crate, labelled “9M342,” the Russian designation for the SA-24 heat-seeking missile.

“These were some of the most advanced weaponry the Russians made,” Mr. Bouckaert said. Referring to the former rebels who have taken control of Tripoli and to the international community, he added, “They need to get people here to secure some of this.”

The SA-24 can be mounted on vehicle-based launchers or fired from a person's shoulder via a much smaller launcher known as a grip stock. The latter configuration, of the same class of weapon as the U.S.-made Stinger, is considered the gravest potential danger to civilian aircraft because the weapon is readily portable and relatively simple to conceal and use.

No grip stocks for SA-24s have yet been found in Libya, and the Russian manufacturer of the SA-24 has previously said that it did not sell any grip stocks to Qadhafi's military. The SA-24s, it said, were sold only with vehicle-mounted launchers. The SA-7, however, is a shoulder-fired missile. A Soviet-era weapon dating to the 1960s that remains in wide use and circulation, it has been implicated in several attacks on airliners over the years, including a failed attack on an Israeli charter plane

Former Eastern bloc nations call it Strela, for the Russian word for arrow. Nine of the freshly emptied crates found Wednesday were marked with the Eastern bloc designation for the Strela: 9M32M.

Libyan rebels have occasionally been spotted carrying SA-7s, although the weapon has no evident practical use to them, given that the Qadhafi air force was grounded by NATO months ago and that the only military aircraft confirmed in the Libyan skies have been the NATO planes supporting the rebels' advances.

Although only nine crates holding two SA-7s each were found in the schoolbook warehouse, those crates were a part of what evidently were nine different consignments.

In all, those consignments added up to a total of 2,445 crates delivered from Russia to Tripoli, containing 4,890 missiles. However, there was no way to ascertain whether the other crates in those consignments had previously been in this warehouse or in some other part of the country. Many of the other missiles may have been issued to the Qadhafi forces in the field, which for months had a need to defend against aerial attack.

The Times has previously documented that 5,270 SA-7b missiles had been delivered to Libya. Some of those shipments were part of the same consignments found on Wednesday. But according to the stencilled markings on the newly found crates, at least 2,322 of the missiles appear to be from previously undiscovered consignments, meaning that at least 7,592 of the missiles had been sent to Libya. Estimates of the true total run as high as 20,000 such missiles.

A spokesman for the Libyan rebel military, Abdulrahman Busin, said the rebel authorities were aware of the schoolbook warehouse, which is only about a quarter-mile from the headquarters of the Khamis Brigade, an elite loyalist military unit headed by a son of Qadhafi. Mr. Busin said that the rebel “military police” had probably removed the missiles.

“The military police were aware of this and they took charge of it; they're the ones who secured it,” Mr. Busin said.

But if that was the case, he was unable to explain why the facility remained unguarded on Wednesday. And efforts were unsuccessful to contact the head of the military police to confirm if his forces indeed had the missing missiles. — New York Times News Service

More In: Comment | Opinion