When Moammar Gaddafi renounced chemical weapons in 2003, the Libyan dictator surprised skeptics by moving quickly to eliminate his country’s toxic arsenal. He signed international treaties, built a disposal facility and allowed inspectors to oversee the destruction of tons of mustard gas.

But Gaddafi’s public break with weapons of mass destruction was not all that it seemed. Only after his death in 2011 did investigators learn that he had retained a large stash of chemical weapons. In a hillside bunker deep in Libya’s southeastern desert, Gaddafi had tucked away hundreds of battle-ready warheads loaded with deadly sulfur mustard.

The story of Gaddafi’s deception now looms over nascent efforts to devise a plan for destroying the chemical arsenal of Syrian President Bashar al-
Assad, another strongman who, in a stunning reversal, agreed in principle last week to give up his stockpile under U.S. and Russian pressure.

Arms control experts say the experience of Libya and other former chemical weapons states such as Iraq could be instructive — in ways good and bad — as diplomats map out a path for finding, securing and destroying Syria’s estimated 1,000 metric tons of chemical agents. Many also fear that clearing Syria of its chemical weapons could prove to be uniquely challenging, in part because the inspectors would be dropped into the middle of a war zone.

“Never has there been an experience like this one,” said Daryl Kimball, director of the Arms Control Association, a Washington-based nonprofit organization. “With Syria, you have a country that did not even acknowledge having chemical weapons until recently. It had no intention of giving up its arsenal until there was a threat of military force. The schedules are being accelerated. And there’s a civil war going on.”

The task of eliminating weapons as dangerous as sarin or VX can be onerous even in the best of circumstances. The United States, which agreed 20 years ago to eliminate its vast, Cold War-era stockpile, still has not completed the task despite spending billions of dollars on state-of-the-art incinerators. Russia, too, is years behind schedule in eliminating an arsenal that once contained 40,000 metric tons of toxic compounds. A handful of other countries, including Japan, India and Albania, have also destroyed their chemical arsenals.

Yet weapons experts point to the successes in Iraq after the 1991 Gulf War and, ultimately, in Libya — two countries in which inspections teams overcame obstacles on their way to destroying large chemical arsenals. Iraq’s weapons programs were scrutinized by two separate U.N.-
appointed inspections regimes, one from 1991 to 1997 and another from 2002 to early 2003, before U.S. forces invaded the country in part because of a belief that Iraq still retained weapons of mass destruction.

In what was perhaps a preview of events in Syria, weapons officials in Iraq managed to complete the task in spite of local hostility and widespread chaos in a country shattered by war, said Charles Duelfer, a leader of the Iraq Survey Group, which searched for weapons of mass destruction in Iraq after the 2003 invasion. The group found and secured a small quantity of abandoned and damaged chemical weapons but uncovered no evidence of ongoing programs.

“Because we had bombed the hell out of the place, the Iraqis didn’t even know what their inventory was,” Duelfer said in an interview. By contrast, he said, “in Syria, it will be up to the government to do a lot of the heavy lifting, including providing protection for the inspectors.”

While many details for the Syrian operation have not yet been finalized, ultimate responsibility will likely fall to a U.N. team, which will include officials of the Organization for the Prohibition of Chemical Weapons.

The Hague-based OPCW verifies compliance with the Chemical Weapons Convention, the treaty that Syrian officials pledged to sign last week. The Syrian government, prodded by its ally Russia, acknowledged its chemical stockpile and promised full transparency in an apparent bid to avert a U.S. military strike over last month’s alleged sarin gas attack in the suburbs of Damascus, the country’s capital. The Obama administration says the attack is responsible for the deaths of more than 1,400 civilians.

The OPCW, which maintains permanent teams of inspectors as well as experts in the science of destroying chemical weapons, was tapped in 2004 to oversee the dismantlement of Libya’s chemical stockpile, which at the time was estimated to include nearly 25 metric tons of mustard gas in addition to ordnance, manufacturing facilities and some 1,400 tons of chemical precursors. The agency’s teams already had verified the destruction of half of Gaddafi’s arsenal when their work was halted by the outbreak of civil war in early 2011.

What chemical weapons does Syria have?

Up to that point, both the Gaddafi government and the OPCW teams were generally given high marks for their work in the elimination of Libya’s chemical weapons. Despite delays and missed deadlines, the Libyan government’s cooperation in the effort seemed genuine, reflecting the will of the autocratic and eccentric Gaddafi, who appeared to believe that his public repentance would end his country’s isolation from the West.

In contrast to Syria, the task in Libya was a professional, unhurried affair, well-suited for management by international bureaucrats, according to scholars and weapons experts.

“Gaddafi’s renunciation of his WMD program came as a result of a months-long diplomatic effort,” Kimball said. “It was not a wartime situation. And there was not a sense of urgency, of the kind we’re seeing now.”

But the Libyan experience also exposed a key weakness: The inspectors had limited authority and means to investigate cheating and no legal tools for holding noncompliant countries to account. While U.N.-appointed inspectors in Iraq were empowered in 1991 to pursue tips, including intelligence from Western governments, the relatively toothless inspectors in Libya were restricted in their ability to search for any hidden sites that might exist.

Indeed, one did: Gaddafi’s secret cache was discovered by opposition forces in an unguarded desert bunker shortly after Gaddafi’s overthrow and death in October 2011. Amateur videos by rebel soldiers showed camouflaged bunkers filled with row after row of green ammunition cases, each containing warheads filled with mustard gas.

The new Libyan government made a formal declaration to the OPCW and promised to destroy the weapons. The effort, like those of Russia and the United States, is lagging behind schedule.

Secretary of State John F. Kerry appeared to acknowledge that the OPCW’s usual powers would have to be broadened in Syria. At a news conference Saturday in Geneva, he said inspection teams would have an “immediate and unfettered right to inspect any and all sites” inside Syria.

“We have committed to a standard that says, ‘Verify and verify,’ ” Kerry said.