Senior Israeli defense official Amos Gilad said Sunday that Syria remains in control of its chemical weapons arsenals, even as the Israel Defense Forces considers a possible attack meant to prevent those arms and advanced Syrian missiles from falling into militant hands.

Gilad said Israel fears that Syria's large chemical stocks could be seized by Lebanese militants, al-Qaida-affiliated radicals or other unspecified "irresponsible elements" operating in Syria.

Gilad told Army Radio on Sunday, "Right now, they (the Syrians) are protecting these arsenals as best as they can."

But over the weekend, Defense Minister Ehud Barak said in a television interview, "I've ordered the Israeli military to prepare for a situation where we would have to weigh the possibility of carrying out an attack" against Syrian weapons arsenals.

On Sunday, Barak said Israel will not allow Syria's chemical weapons to fall into the hands of radical Islamist groups such as Hezbollah. "Israel will not be able to accept the transfer of smart weapons" to the Iranian-backed radical Shiite movement in Lebanon, he told reporters at an army base near Tel Aviv.

Asked about an earlier remark, in which he said the Israeli army had been ordered to prepare for a scenario of an operation on Syrian soil to secure the weapons, he said: "It wouldn't be right to say here when we will act, if we will act, how we will act." Israel would defend itself "with responsibility", he added.

The United States is closely monitoring Syria's chemical weapons stockpile and is "actively consulting" Damascus's neighbors to stress concerns over the security of those weapons and Syria's responsibility to safeguard them, the White House said on Saturday.

"We believe Syria's chemical weapons stockpile remains under Syrian government control," White House spokesman Tommy Vietor said. "Given the escalation of violence in Syria and the regime's increasing attacks on their people, we remain very concerned about these weapons."

That was the White House response to a question about a Syrian military defector's claim that President Bashar Assad's forces were moving chemical weapons across the country for possible use against the opposition in a military retaliation for the killing of four top security officials.

"In addition to monitoring their stockpiles, we are actively consulting with Syria's neighbors - and our friends in the international community - to underscore our common concern about the security of these weapons, and the Syrian government's obligation to secure them," Vietor said.