| THE HAGUE
THE HAGUE With an uprising in Syria loosening the grip of president Bashar al-Assad, world powers are worried that he could lose control of a secret stockpile of chemical weapons, giving militants access to deadly poison gas.
Syria is one of just eight states - along with its arch foe Israel and nearby Egypt - that have not joined the 1997 Chemical Weapons Convention, which means the world's chemical weapons watchdog has no jurisdiction to intervene there.
Western countries believe that Damascus has the world's largest remaining stockpile of undeclared chemical weapons - including mustard gas and the deadly VX nerve agent - which Assad maintains as a counterbalance to Israel's undeclared nuclear arsenal.
The Syrian army is trained to use poison gas and, according to US and Israeli intelligence, can deploy it on long-range missiles. In a sign of growing concern, an Israeli factory was refinanced to ramp up production of gas masks to prepare for a possible attack, an Israeli member of parliament told Reuters.
"The arsenal, based on reports, is quite alarming," Ahmet Uzumcu, head of the Organisation for the Prohibition of Chemical Weapons (OPCW), said in an interview with Reuters.
"If those reports are correct it would really take a lot of resources and efforts to destroy, to eliminate, those stocks."
Syrian unrest undermines Assad's ability to secure his arsenal from armed groups - such as his Shi'ite Muslim regional ally Hezbollah, or the Sunni militants among his opponents.
In Washington, General Martin Dempsey, chairman of the Joint Chiefs of Staff, described Syria's stockpile as a major source of concern for the United States, which he said had prepared contingency plans with regional partners.
The main threat, Dempsey told the House Armed Services Committee last month, is Syria's "proliferation or the potential proliferation of chemical and biological weapons - that is to say weapons of mass destruction."
Because it has not signed the chemical weapons ban treaty and the United Nations has not intervened, Syria is under no international obligation to declare its chemical weapons, give them up or allow inspectors to monitor them.
"There is a very odd silence in the corridors of the OPCW about Syria, even though several individual countries have expressed grave concerns," said an OPCW official.
"The silence doesn't mean there is a lack of concern. It is definitely the 800 pound gorilla in the room," he said. "Syria is the overriding source of concern for chemical weapons in the world right now."
With the OPCW's hands tied, the only international forum to discuss Syria's chemical weapons would be the U.N. Security Council, where officials said the issue has not been raised.
In late February, Uzumcu met U.N. Secretary General Ban Ki-moon. They "noted with concern the reports on the possible existence of chemical weapons," but took no further action.
Uzumcu said his teams could deploy within 12 hours for an inspection were they given an order by the United Nations.
"That would obviously require some preparedness for some specific cases like Syria...but chemical weapons are chemical weapons, so this is well known to our experts," Uzumcu said.
Syria has joined the 1925 Geneva Protocol, which prohibits first use of chemical or biological weapons, but does not mention production, storage or transfer of them.
The OPCW, the Hague-based organization founded to oversee a ban on the production, stockpiling and use of chemical weapons, has 188 member nations, but has struggled to bring on board countries in the Middle East, where poison gas has been used repeatedly since the 1960s.
Egypt deployed phosgene and mustard gas against Yemeni royalist forces in the mid 1960s. It has not reported the destruction of chemical agents or weapons to the OPCW.
Iraqi dictator Saddam Hussein killed thousands of Iranians and Iraqi Kurds in more than a dozen poison gas attacks during the Iran-Iraq war in the 1980s. In March 1988 Iraq dropped canisters of Tabun, Sarin, VX and mustard gas, killing 5,000 villagers in the Kurdish town of Halabja.
U.S. and British suspicion that Saddam still possessed chemical and biological weapons - despite being ordered by the Security Council to give them up - became the justification for the 2003 invasion to topple him.
After the invasion no banned weapons were found, seriously damaging the credibility of Washington, London and their intelligence agencies.
Libya, which developed a chemical weapons program under the late leader Muammar Gaddafi, is set to resume destroying tonnes of ageing mustard gas later this year with the help of the OPCW.
A weakened Assad could have difficulty keeping weapons out of the hands of others, and a desperate Assad might be more inclined to use them or give them to allies.
"The most dangerous possibility is that unrest in Syria degrades the state's capability to maintain security to the point where not all the chemical weapons stockpiles are secure," said Ayham Kamel, Middle East analyst at consultancy Eurasia Group. "The nightmare scenario is that they fall into the hands of al Qaeda."
"Syria could try to break the regional balance of power by supplying Hizbollah with an arsenal that could threaten Western interests," Kamel said.
If the conflict crosses borders, Assad's conventional forces are not as powerful as those of Israel or NATO ally Turkey, "so there is a need to use asymmetrical warfare, and chemical weapons could be used," Kamel added.
Israel, which fought four wars with Syria since 1948, feels most threatened. Israel's premier think-tank, the Institute for National Security Studies, reassessed the risk in a review of the regional security implications of "Arab Spring" uprisings.
"Syria is considered a superpower in the chemical and biological realm...The chemical weapons are stored, protected, and controlled by al-Assad's loyal forces," it said.
If the stockpiles are obtained by organizations such as the Taliban, Hizbollah, al Qaeda or Hamas, "it will be more likely that such weapons will be used in some scenario in the region."
Those fears prompted Israel to provide 80 million shekels (about $20 million) in government support to a gas mask factory to secure production until the end of the year.
Roughly 60 percent of Israelis were supplied with the protective gear before the factory ran into financial troubles and was nearly closed, said Zev Bielski, an opposition lawmaker on the parliamentary panel for homefront war-readiness.
"The risk will be greater as violence continues to escalate," said Anthony Skinner, Middle East analyst at Maplecroft, a consultancy firm.
"We are more concerned about opportunistic Islamist militants seeking to exploit the turbulence, get their hands on chemical weapons and smuggle them out of the country."
(Reporting by Anthony Deutsch, Dan Williams, Louis Charbonneau, Missy Ryan, and Peter Apps.)