The United States could try to secure Syria's chemical arsenal by sending in special forces and staging bombing raids but any military action would be high-risk with a chance that weapons might fall into the wrong hands, experts and former officials said Tuesday.
As opposition forces steadily gain ground in Syria, Washington and its allies worry that President Bashar al-Assad's regime may turn to chemical weapons in desperation or that extremists may get hold of artillery rounds filled with sarin or mustard gas.
Western powers issued stern statements on Monday and Tuesday, with President Barack Obama warning Assad: "If you make the tragic mistake of using these weapons, there will be consequences and you will be held accountable."
But ex-intelligence officers and analysts say military intervention carries a host of dangers and difficulties.
Air strikes against chemical weapon production sites and storage depots would carry the risk that "some chemical agents would likely be released into the air, endangering nearby civilians," while still failing to destroy all the munitions, Michael Eisenstadt wrote in a report for the Washington Institute for Near East Policy.
Bombing, however, could block entrances to chemical arms bunkers carved into mountainsides and effectively entomb chemical agents, according to Eisenstadt.
"It's difficult to come up with a viable scenario where you do this without putting troops on the ground," said David Hartwell, an analyst with IHS Jane's, a defense and security consultancy.
"If your aim is to secure chemical weapons, you can't do that from the air," he told AFP.
But deploying ground troops still would require warplanes to knock out Syrian air defenses, allowing the special forces teams to be flown in, experts said.
Some media reports previously speculated that up to 75,000 troops would be needed to search for and safeguard chemical weapons. But it remains highly unlikely the Obama administration would be ready to back such a large military presence in another Arab country in the aftermath of the Iraq war, experts said.
A more plausible scenario could see small teams of US, British and French special forces advising a force from Turkey and other Islamic nations, including Jordan, Hartwell said.
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"The US provides the advice, the logistics and the back-up, where as the boots on the ground would be provided from somewhere else," he said.
The Pentagon has already sent a contingent of about 150 special forces to Jordan to help with a range of contingencies, including a possible mission to secure the Assad regime's chemical stockpiles.
If US special forces were called on, they would probably swoop in to carry out pinpoint raids without remaining on Syrian territory, said Jeffrey White, a veteran of the Defense Intelligence Agency.
Much would hinge on the accuracy of US and Western intelligence, said White, now with the Washington Institute for Near East Policy.
During the first Gulf war in 1991, American forces -- fearing Saddam Hussein's regime would unleash a chemical attack -- struggled to track down Scud missile launchers in the western desert of Iraq.
But US spy agencies may have a better handle on Assad's stockpiles since the former head of the chemical weapons program, Major General Adnan Silou, defected in July, and the Pentagon expressed confidence that it did.
"The US government has good visibility into the chemical weapons program and we continue to monitor it," spokesman George Little said.
However, chemical agents kept at a storage site are one thing and artillery rounds or rockets armed with chemical agents are another.
"These chemical weapons are not big things. They can be put in the back of any truck. There are thousands of military trucks rolling all around Syria every day," White said.
"How are you going to know which trucks have these chemical weapons?"
He added: "One 152 millimeter artillery battery looks like any other."
Instead of attacking elusive, dispersed targets, the best option may be to take aim at the heart of the regime, hitting the army's command network if it tries to use chemical weapons, White suggested.