U.N. vehicles transport a team of experts from the Organisation for the Prohibition of Chemical Weapons as they leave their hotel in Damascus October 5, 2013. (KHALED AL-HARIRI/REUTERS)

Syria appears to be moving its chemical weapons to a small number of central locations, U.S. officials say, in a sign that the regime is preparing to cooperate with an international effort to rapidly destroy its entire arsenal of deadly toxins.

The movement of chemicals and equipment in recent days — which initially spurred fears that Syrian officials were trying to hide parts of their stockpile — suggests instead that the weapons are being consolidated ahead of a first visit by inspection teams that arrived in the country last week, administration officials said.

The activity has contributed to a cautious optimism among U.S. officials over the prospects for quickly dismantling the chemical arsenal. Syrian officials a week ago turned over their first inventory of chemical weapons and storage sites, a list that U.S. analysts described as detailed, although incomplete.

The records have helped shed light on a sizable Syrian stockpile that U.S. officials say contains hundreds of tons of precursors for the nerve agents sarin and VX, as well as a surprise: ricin, a highly lethal poison derived from castor beans.

“There are encouraging signals, but we are really in the first weeks of the process,” said a senior State Department official with detailed knowledge of the plans for eliminating Syria’s chemical stockpile.

Working with Russian counterparts, U.S. officials are preparing to implement a phased plan that they say could eliminate most of Syria’s capacity to produce chemical weapons within a few weeks, said the official, who, like others interviewed, insisted on anonymity to discuss the diplomatically sensitive operation.

The plan calls for physically destroying production equipment — in some cases with sledgehammers — and then using mobile decontamination machines to neutralize the chemicals themselves.

But the official, along with other U.S. officials and experts briefed on the Syrian program, acknowledged numerous potential obstacles, including the possibility that Syria could change its mind and seek to thwart or deceive the inspectors. Moreover, the Obama administration has not reached an agreement with a third government — not yet identified — to allow tons of sarin precursors to be brought to that country for destruction, the officials said.

“It could go off the rails in many ways,” the State Department official said. “But we are planning for success, under ideal or difficult circumstances.”

U.S. and Russian officials sketched out a framework for destroying Syria’s chemical stockpile during negotiations last month in Geneva, talks that found the two countries largely in agreement on the size of the arsenal and how quickly it can be destroyed. At the time, the Obama administration was threatening to launch a military strike against President Bashar al-Assad’s government as punishment for its alleged Aug. 21 sarin attack east of Damascus that killed more than 1,000 civilians.

Russian and American technical experts — some of whom had worked together on dismantling Cold War-era weapons stockpiles — have since reached agreement on a rough order of business for the Syrian mission. The highest priority, U.S. officials say, is to quickly dismantle key components of Syria’s weapons program so that Assad is effectively denied the use of his chemical arsenal, even before all its components are destroyed.

The work would start with smashing machines used to produce and mix the chemical precursors for nerve agents, U.S. officials and weapons experts said.

“This is relatively simple: You need bulldozers and sledgehammers,” the senior State Department official said. “It can be done by Syrians with international supervision.”

Another easy step is dumping or burning vats of a relatively harmless alcohol that is the final additive in the making of deadly sarin. A tougher challenge is getting rid of sarin’s other major component, a highly corrosive chemical broth that is hazardous to humans and to the environment.

Russia and the United States, which are in the process of destroying their own stocks of Cold War-era sarin, have offered to provide special equipment and expertise. The U.S. Army’s Edgewood Chemical Biological Center has developed a mobile unit, small enough to fit inside two standard shipping containers, that can convert sarin’s precursors into a less-toxic form that can be safely incinerated, U.S. officials and experts say.

The Obama administration hopes that most of the precursors can be taken out of the country to be neutralized. A small number of sarin-filled rockets and shells in Syria’s arsenal would likely be destroyed inside Syria, as would the country’s estimated 300 metric tons of sulfur mustard — a blister agent used during World War I.

Two U.S. officials familiar with Syria’s weapons program confirmed that Syria had manufactured ricin, a toxin that is outlawed under both chemical and biological weapons treaties. The officials said Syria appears to have been unable to find an effective means of weaponizing the ricin.

The task of destroying the sarin-filled warheads could stretch on for months, because many will have to be individually drained and decontaminated. But U.S. officials are confident that the last of the shells and rockets can be eliminated by late June, provided that the Syrian government provides uninterrupted access to weapons facilities and honors commitments to protect the inspection teams.

“In this regard, the Russian commitment is of great importance,” the senior State Department official said. “It is clear that they understand the leverage they have over the Syrian government. We expect them to use it.”

Despite the reported progress, some weapons experts remained skeptical that Assad would allow his entire arsenal — originally intended as Syria’s strategic hedge against its more powerful adversary, Israel — to be fully eliminated. Amy Smithson, a weapons expert with the Washington-based James Martin Center for Nonproliferation Studies, recalled the deceptive practices used by another Middle Eastern autocrat, former Iraqi leader Saddam Hussein, in hiding evidence of his weapons programs from international inspectors.

“The twisted reality is that Assad could use the rights afforded to him under the Chemical Weapons Convention — which Syria acceded to on Sept. 14 — to thwart the work of the Organization for the Prevention of Chemical Weapons,” the Hague-based organization that is leading the inspections, Smithson said.

Like Saddam, Assad has “rolled out the welcome mat for inspectors, then stalled them while trying to destroy incriminating evidence,“ Smithson said.

But other experts saw a tangible, if complex, opportunity to eliminate one of the world’s largest chemical arsenals in a manner that could lead to other breakthroughs in international arms control.

“Of course, eliminating Syria’s chemical weapons is hard, but it is doable and we must try,” said Joseph Cirincione, president of the Ploughshares Fund and author of several books on weapons of mass destruction.

“This is already going much better than anyone predicted. Assad is now cooperating and under tremendous pressure to continue to do so,” Cirincione said. “He will undoubtedly try to cheat, to hide some weapons, but their military significance will be marginal. And the penalty for use, substantial.”