U.S. intelligence agencies are closely watching Israel’s military for signs it will conduct strikes on Syria’s stockpiles of chemical weapons, amid concerns the deadly nerve agents could fall under the control of Hezbollah or al Qaeda terrorists, U.S. officials said.

Syria’s arsenal remains vulnerable as the result of the internal conflict currently underway in Syria between government forces and opposition rebels, one official said.

"Everyone suspects Syria maintains an active chemical weapons program; and it would be dangerous not to plan accordingly," the official said.

As for concerns the weapons will be captured or transferred, the official said: "Most countries that have CW stocks view it as a strategic, not tactical, tool—and strategic tools are usually pretty well protected and aren't given away lightly."

However, other U.S. officials said special operations forces are prepared to take action inside Syria in the event the regime falls and the country spirals further into chaos. The teams would seek to secure or destroy stockpiles of chemical arms to keep them from being taken over by terrorists. Hezbollah has been very active in Syria, and there are reports that al Qaeda terrorists have moved into Syria during the current crisis.

The exact size of the Syrian chemical arsenal is not known. The Center for Strategic and International Studies reported several years ago that Syria has stockpiled 500 to 1,000 metric tons of chemical agents. The weapons are said to include long-lasting VX nerve agent and less-persistent Sarin nerve agent, as well as mustard blister agents.

Most but not all of the weapons stockpiles are known to U.S. intelligence agencies.

The New York Times reported Thursday that CIA operatives are working in southern Turkey to coordinate foreign assistance to Syrian rebel forces.

Recent statements by senior Israeli military officials prompted U.S. concerns over an Israeli strike on Syria.

Senior officials in Israel told the newspaper Yedioth Ahronoth that if Syria’s army gave chemical weapons to Hezbollah or other terrorists an Israeli attack would be needed.

The newspaper reported May 31 that Israel failed to prevent Syria’s transfer of M-600 rockets to Hezbollah and the weapons can now threaten central Israel. One military source was quoted as saying that mistake would not be repeated.

Israeli Maj. Gen. Yair Golan, commander of forces deployed on the Syrian and Lebanese front, was quoted in press reports expressing concerns about Syria being used as "a warehouse for war materiel that feeds terrorist elements in the region."

Golan also said there were reports that al Qaeda terrorists are working against the regime in Damascus and those terrorists eventually would target Israel, perhaps in the coming months.

IDF Deputy Chief Maj. Gen. Yair Naveh also said June 11 that Israeli forces must be on alert because Syria’s military has "the largest chemical weapons arsenal in the region, which can reach any spot in Israel." He expressed worries that the weapons could "fall into the hands of the rebels or the terrorists."

A State Department arms compliance report from 2010 stated that Syria is also believed to have an offensive biological weapons program in addition to the chemical arms.

Calls for military intervention could increase if Syrian forces begin using the deadly chemical weapons in battling opposition forces.

A Syrian rebel leader, Col. Riad al-Asaad of the Syrian Free Army, told Al Jazeera June 8 that Syrian military aircraft had dropped chemical bombs that poisoned people, and that government forces had distributed gas masks to troops 10 days earlier in preparation for the use of the weapons against northern areas of the country.

State Department cables disclosed last year revealed Syria had obtained large quantities of chemical weapons precursor agents from China, Italy, and other states.

A July 10, 2008, cable said: "While Syria proclaims its desire to cooperate with the IAEA in investigating serious evidence of a covert nuclear program and allowed an extremely restricted June 22-25 IAEA visit to investigate a covert nuclear program, Syria has never accounted for its [chemical weapons] stocks, refuses to join the Chemical Weapons Convention, and is modernizing its long-range missile systems in cooperation with Russia, North Korea, and other countries."

"There remain suspicions Syria could be sharing missile technology with Hezbollah," the cable said, noting, "Just as Washington has done in past demarches regarding Syrian WMD and missile programs, Post believes a new scrub of releasable intelligence would strengthen our arguments regarding the gap between Syrian rhetoric and actions."

A June 20, 2006, cable reported that Iran was assisting Syria’s chemical warfare program with construction of four to five precursor chemical production facilities.

"Iran would provide the construction design and equipment to annually produce tens to hundreds of tons of precursors for VX, sarin, and mustard," the cable said.