Updated 5:51 p.m. ET, 11/5/2013

By Barbara Starr

The United States is looking at new classified intelligence indicating the Syrian government may not fully declare its chemical weapons stockpile, CNN has learned. That would mean it will still have a secret cache of chemical weapons even after the current agreed-upon destruction effort is carried out.

The intelligence is not definitive but “there are various threads of information that would shake our confidence,” one U.S. official said. “They have done things recently that suggest Syria is not ready to get rid of all their chemical weapons.”

CNN has spoken to several U.S. officials with access to the latest intelligence on Syria, who confirmed the information. All declined to be identified because of the sensitivity of the data. U.S. intelligence agencies, the Defense Department, the State Department and White House are all reviewing the information.



One official cautioned there is not yet a definitive U.S. conclusion about Syrian intentions based on this intelligence, but there is an effort to gather corroborating information and better understand what the regime may be up to.

There is agreement among U.S. officials that Syria’s official declarations to the Organisation for the Prohibition of Chemical Weapons (OPCW) have been made largely in good faith after the threat of military action by the United States for Syria’s use of chemical weapons against civilians. The United States believes Syrian President Bashar al-Assad understands not to do that again.

National Security Council spokesperson Bernadette Meehan issued a statement Tuesday evening saying: "We continue to review and assess the completeness and accuracy of Syria's declaration to the OPCW. However, in accordance with OPCW regulations, Syria's declaration is confidential, and we will not publicly discuss its details or our assessment of it. For further details, we would refer you to the OPCW."

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Officials told CNN the new intelligence is related to stockpile inventories and delivery systems, such as warheads and artillery shells - items that could preserve Syria’s ability to use chemical weapons again if it chose to. Officials believe al-Assad will hold on to some of the chemical weapons largely as a long-term hedge against what he sees as a threat from Israel.

“It strains credulity,” one official said, to believe he will readily give up his entire chemical weapons program.

Officials would not say exactly how the latest intelligence was collected. But much of U.S. intelligence about Syria comes from satellite imagery. Also, there have been communications intercepts in the past that have given the United States clues about the intentions of the Syrian leadership. And U.S. officials have in the past confirmed channels of information from operatives on the ground who work on behalf of the Syrian opposition or other countries in the region.

Al-Assad may try to hold on to more than just weapons. Last week, Foreign Policy magazine reported that Syria's foreign minister had asked the OPCW to spare a dozen of Syria’s chemical weapons factories from destruction so they could be converted into civilian chemical facilities. Asked about that report Friday, State Department spokeswoman Jennifer Psaki said it did not appear Syria had submitted a formal request to OPCW. "The OPCW would then consider any request,” Psaki said. “However, as you know, the (U.N. Security Council) and the OPCW Executive Council decision made clear that Syria’s chemical weapons program must be eliminated."

Asked about the Foreign Policy report, a U.S. official said, "there's a real concern that the Syrians might be trying to preserve some of their CW capabilities."

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The new intelligence is not related to Syria's reported desire to keep some of its chemical factories.

The OPCW has endorsed shipping chemical stockpiles out of the country for destruction because of the ongoing conflict there. Discussions on finalizing a plan are expected in the coming days, according to the organization.

The OPCW had previously announced the destruction of production equipment at all declared chemical weapons production, filling and mixing facilities. According to the OPCW on Tuesday, 21 of the 23 sites have been inspected. The items from the other two – inaccessible because of the conflict –were moved to accessible areas and verified against disclosure statements made by the regime.

The OPCW also said 154 warheads have been destroyed by the Syrians. Destruction work has begun at five other sites which the Syrians say hold 424 bombs and 63 warheads.

Norway had considered a U.S. request that the Scandinavian country take some of the chemical weapons inventory for destruction. But last month, the Ministry of Foreign Affairs announced it rejected the plan due to “time constraints and external factors” such as regulatory requirements.

So far the United States has provided $6 million in assistance to the OPCW efforts, including 10 armored civilian vehicles to transport inspectors inside Syria.

Meanwhile, the Pentagon is looking at offering technology it has developed for any OPCW-sponsored chemical weapons destruction. The first detailed public hint of that came Tuesday from Defense Secretary Chuck Hagel, who said, “DoD has not only maintained military pressure on the Assad regime, it has also developed the technology that may very well be used to destroy these chemical weapons.”

Hagel was referring to the Field Deployable Hydrolysis System, a series of containers full of high-tech equipment that can be sent into the field. Rather than use the typical incineration technology to destroy chemical agents, this system neutralizes the chemical weapons by mixing them with water and other agents.

One concept is to send the system to a third country, where the Syrian chemical weapons would also be shipped, a Defense Department official said. The Pentagon is currently analyzing what would be needed to put the chemical weapons on a ship to transport them to a third country willing to accept the material for destruction. The concerns are both how to keep the material stable during shipment and providing maritime security for the transit.