Syrian President Bashar Assad responded to past warnings about the security of chemical weapons by taking steps to keep them out of the hands of militants, Israel's vice prime minister Moshe Yaalon said on Wednesday.
Yaalon joined Prime Minister Benjamin Netanyahu in making clear that Israel is as concerned about chemical weapons falling into the hands of anti-Assad insurgents as it is about them being used by state forces in the Syrian civil war.
"Together with the international community, we are closely monitoring developments in Syria regarding its stores of chemical weapons," Netanyahu said on Tuesday. "Such weapons must not be used and must not reach terrorist elements."
In an interview with the Israeli news website Walla that was posted on his Facebook page, Yaalon said: "There is speculation that the chemical arsenal will fall into the hostile and irresponsible hands of the likes of al Qaeda or other terrorist groups.
"In the past, clear messages were relayed to Assad on a number of opportunities, and in response Assad in fact gathered up the weaponry and separated the materials," Yaalon said.
Yaalon confirmed that the United States had spotted "suspicious activity" involving Syria's stockpile, hence the warning to Assad from President Barack Obama and European allies meeting at NATO headquarters that they must never be used.
U.S. Secretary of State Hilary Clinton said on Wednesday the United States was worried an "increasingly desperate" Assad could resort to the use of chemical weapons against rebels, or lose control of them "to one of the many groups that are now operating within Syria".
Clinton said Washington had made clear to Syria that the use of chemical weapons would be a "red line" for the United States.
Syria refuses to acknowledge possession of chemical arms but has said repeatedly it would not use such weapons on its own people, though it might against foreign attackers. Israel and NATO countries say Syria has stocks of various chemical warfare agents in four sites.
Syrian rebels who have been fighting for the past 20 months to topple Assad have recently overrun some Syrian military bases. Radical Islamist groups which included foreign Jihadi fighters are a powerful force in the revolution.
Reporting by Dan Williams; Writing by Douglas Hamilton; Editing by Erika Solomon and Andrew Roche