Libyan rebels prepare their weapons to fight against Col. Moammar Gaddafi’s forces, in this photo from March 2011. Experts say vast quantities of weapons and fighters that streamed out of Gaddafi’s arsenals are helping aid the crisis in Mali and Algeria. (ARIS MESSINIS/AFP/GETTY IMAGES)

The hostage standoff at an Algerian gas field has thrown a fresh spotlight on the spillover unleashed by the 2011 war that toppled Moammar Gaddafi in Libya.

Experts say the vast quantities of weapons and fighters that streamed out of Gaddafi’s arsenals may have served as a catalyst for the region’s expanding crisis.

But the bold move on the gas complex near the Libyan border this week, coupled with the swift military successes of militants in Mali, have also raised questions about NATO’s handling of Libyan arsenals, as well as the country’s borders, during the eight-month revolution, in which the alliance assisted Libya’s rebel forces.

Some experts say that NATO forces and the U.S. government were so consumed by the threat of surface-to-air missiles in the wake of Gaddafi’s fall that they failed to halt the proliferation of the ordinary high-caliber weapons that may now be fueling Mali’s Islamist insurgency and could carry drastic implications for a region already reeling from lawlessness and a growing al-Qaeda threat. Some of those weapons have already reached Syria and the Gaza Strip.

While it is impossible to measure the exact role that Libya’s revolution and the ensuing security vacuum played in the recent unrest, analysts say that without the arrival of Libyan weapons and trained fighters, it would have been far more difficult for Mali’s extremist groups to seize control of the country’s vast desert north.

“The weapons proliferation that we saw coming out of the Libyan conflict was of a scale greater than any previous conflict — probably 10 times more weapons than we saw going on the loose in places like Iraq, Somalia and Afghanistan,” said Peter Bouckaert, emergencies director at New York-based Human Rights Watch, who documented the disappearance of weapons from Gaddafi’s arsenals during the war.

The late Libyan dictator spent four decades amassing one of the most formidable arms supplies in Africa, analysts say. As Libyan rebels gradually seized control of the country in 2011, massive caches ­of mortars, missiles, rocket-
propelled grenades and explosives were often left unattended and open for looting.

Bouckaert recalled conversations with U.S. government contractors whose top priority was surface-to-air missiles, often referred to as man-portable air-
defense systems, or MANPADs. Their eyes “glazed over,” he said, when the topic shifted to the flow of the kinds of machine guns and other small arms that have since appeared in footage of extremist groups in northern Mali.

“The international community failed to act effectively to stop that kind of proliferation,” Bouckaert added.

The flow of weapons

The flow of guns and fighters into Mali coincided with collapsing security there after a botched coup last March left the national army leaderless and weak.

A long-simmering conflict between the Tuareg minority in Mali’s north and the government in Bamako was bolstered by the return of Tuareg fighters, who were trained by and fought for Gaddafi’s regime, and brought guns and ammunition as they fled. “One day you have guerrilla forces fighting with AK-47s, and the next moment they’re showing up with anti-aircraft guns and Grad missile systems,” Bouckaert said.

Tuareg nationalists and Islamist militants, including al-Qaeda’s North African affiliate and two other extremist groups, have also boosted their supply of weapons with arms seized from Malian military bases, said Shashank Joshi, a Middle East expert at the Royal United Services Institute, a British think tank.

Libya’s weapons have also seeped beyond the Sahara. In the past year, Egyptian authorities have seized multiple cargos that have included anti-aircraft machine guns, mortars and MANPADs near the border with Libya and in the volatile Sinai Peninsula, which has served as a smuggling route into the Hamas-ruled Gaza Strip.

Libyan weapons and fighters have also found their way into Syria’s conflict, although experts say it has been difficult to assess the impact that Gaddafi’s arms have had there. Though at least one shipment of Libyan weapons is reported to have found its way to Syrian rebels over the summer, far greater quantities have been seized by the rebels from regime armaments or bought on the local black market.

A safe haven in Libya?

Meanwhile, reports of extremist training camps in eastern Libya and a deadly attack by Islamist militants on the U.S. mission in Benghazi in September have stoked fears that Libya could become a safe haven for regional extremist groups.

“Southern Libya is one of those areas that’s going to be very vulnerable,” Joshi said. The desert region has proved difficult to contain for the country’s fledgling government force. “It seems likely that, over time, you’re going to see some of these groups that are facing enormous pressure in Mali being squeezed out,” Joshi said. “One of the places they will go will probably be Libya.”

Spokesmen for the militants who seized hostages at the In Amenas gas complex 40 miles west of the Libyan border said they were acting in retaliation for French airstrikes in northern Mali.

The militants included at least two Libyans and other non-Algerian Arabs, Algerian government sources told Reuters. Algerian authorities also said the militants had requested and were denied safe passage into Libya with their hostages.

Last month, Libya’s weak central government declared its southern region a closed military zone, after government militias and soldiers proved unable to halt outbreaks of tribal violence and smuggling along Libya’s borders.

Massoud Ali Oresh, a tribal leader from the western mountain town of Zintan, said that Zintani forces acting on behalf of the central government in Tripoli have stopped smugglers, including Tuareg, from neighboring countries on and near the southwest border in recent months.

“It is fairly easy [for people to get across] because the border area is wide and they can’t monitor all of that with one checkpoint every couple of kilometers,” Oresh said.

Liz Sly in Beirut and Sharaf al-Hourani in Cairo contributed to this report.