The United States is planning to dispatch dozens of former military personnel to Libya to help track down and destroy surface-to-air missiles from Moammar Gaddafi’s stockpiles that U.S. officials worry could be used by terrorists to take down passenger jets.

The weapons experts are part of a rapidly expanding $30 million program to secure Libya’s conventional weapons in the wake of the most violent conflict to occur in the Arab Spring, according to State Department officials who provided new details of the effort.

Fourteen contractors with military backgrounds have been sent to help Libyan officials, and the U.S. government is looking at sending dozens more. Thousands of pamphlets in Arabic, English and French will be delivered to neighboring countries so border guards can recognize the heat-seeking missiles, the officials said. It could grow to become one of the three biggest U.S. weapons-retrieval program in the world, along with those in Iraq and Afghanistan.

“We have not seen any . . . attacks with loose missiles coming out of Libya yet,” said Andrew Shapiro, assistant secretary of state for political-military affairs. But, he added, “We’re working as assiduously as we can to address the threat. It only takes one to make a real difference.”

Gaddafi was one of the world’s top purchasers of the shoulder-fired missiles, buying about 20,000 in the 1970s and 1980s, according to U.S. estimates. While the weapons are of limited effectiveness against modern military aircraft, the still pose a threat to commercial passenger planes.

Thousands of the missiles were destroyed in NATO bomb attacks on arms depots during the war and hundreds have been recovered by the new government. But an unknown number were carted off by Libyan rebel groups and civilians who swarmed into unguarded storage areas after Gaddafi’s forces were defeated.

Already, several missiles have been intercepted on the desert road from Libya to Egypt, according to Egyptian officials. Tunisia’s prime minister, Beji Caid Essebsi, said in a recent interview he was so worried about smuggled Libyan weapons that he planned to ask Washington to provide helicopters for border surveillance.

Unlike in Iraq and Afghanistan, the U.S. military has no troops in Libya who can secure the weapons. President Obama has refused to deploy U.S. military forces to Libya to avoid raising hackles both in the Middle East and in the U.S. Congress. Some lawmakers — notably House Intelligence Committee Chairman Mike Rogers (R-Mich.) — have called for using U.S. soldiers to secure the shoulder-fired missiles and Libya’s chemical weapons stocks.

But that task is in the hands of an overstretched Libyan transitional government, which has shown willingness but limited capacity.

“We need help,” Atia al-Mansouri, a military consultant to the governing Transitional National Council, said Thursday. Various rebel groups had hauled away the weapons, he said, “and they are a little more powerful than the army.”

Shoulder-fired missiles have emerged as a global threat, with more than 40 civilian aircraft hit by the weapons since the 1970s. After al-Qaeda-affiliated terrorists tried to shoot down an airliner in Mombasa, Kenya, in 2002, the U.S. government stepped up its efforts to track and dismantle the missiles, known technically as MANPADS (Man-Portable Air Defense Systems).

Weapons proliferation experts say Western and Libyan officials didn’t focus enough on ensuring Tripoli’s weapons depots were safeguarded as soon as the capital fell.

“It wasn’t taken that seriously until the looting began full-on,” said Rachel Stohl, an expert on the international arms trade at the Stimson Center think tank. She said U.S. officials should have learned their lesson after thousands of shoulder-fired missiles were taken from Saddam Hussein’s depots in Iraq.

U.S. officials say they’ve done as much as they could, given that much of Libya was under Gaddafi’s control until recently. U.S. officials from President Obama on down raised the issue with the rebel council that declared itself Libya’s interim government in March. Washington gave $3 million in May to two nongovernmental groups trying to secure weapons sites in eastern Libya.

And this summer, U.S. interagency teams visited eight countries in Libya’s neighborhood, offering assistance on improving border controls and airport security and distributing pamphlets depicting various kinds of missiles.

The contractors being sent to Libya, part of a “quick reaction force” overseen by the State Department, will be attached to about 20 teams of security personnel run by its interim government, U.S. officials say. So far, the Americans have surveyed 20 of the former regime’s three dozen known ammunition storage sites, trying to determine what’s missing, officials say. Each of the sites contains hundreds of bunkers.

U.S. officials declined to comment on whether they were contemplating rewards for the return of weapons, as was done in an U.S. program in Afghanistan.

Compared to Afghanistan and Iraq, “it’s just been a very different beast in Libya, given that we haven’t put boots on the ground . . . nor has the host government wanted us to. It has to be a cooperative effort, with the agreement of the TNC,” said one State Department official, who was not authorized to comment on the record.

U.S. officials are also appealing for help from their European allies. Britain has sent a small military team to help find and dismantle the missiles. “This is a matter of urgency,” Defense Secretary Liam Fox told the British parliament this week.

So far, the Libyan-led teams have recovered hundreds of the missiles. “We are committed to destroying such weapons,” Brig. Mohamed Hedayah, head of the armament department in the national army, told Reuters.

But rebels in Libya say hundreds or thousands are now outside the interim government’s reach. Essam Abu Bakr, 33, who fought with rebels trying to oust Gaddafi, now guards a dusty weapons site in Tripoli littered with boxes from Kalashnikov rifles and 7.62mm bullets looted after Gaddafi forces were routed. He recalled watching groups of rebels at a nearby military base toss crates of grenades and missiles into trucks “as though they were sacks of sugar.”

“I’m worried,” he said. Loose weapons, he said, “are everywhere.”