“We've picked up several indications which lead us to believe that they're combining chemical precursors,” the official said, on condition of anonymity, adding that the operation was apparently aimed at making sarin.
U.S. President Barack Obama directly warned Syria’s President Bashar al-Assad Monday that he would face “consequences” if he made the “tragic mistake” of turning chemical weapons on his own people.
“Today, I want to make it absolutely clear to Assad and those under his command, the world is watching. The use of chemical weapons is and would be totally unacceptable,” Obama said.
Earlier, a senior U.S. defense official said U.S. and allied intelligence have detected Syrian movement of chemical weapons components in recent days, the Associated Press reported, as the Obama administration strongly warned the Assad regime against using them.
A senior defense official said intelligence officials have detected activity around more than one of Syria’s chemical weapons sites in the last week. The defense official spoke on condition of anonymity because he was not authorized to speak publicly about intelligence matters.
Secretary of State Hillary Rodham Clinton, in Prague for meetings with Czech officials, reiterated President Barack Obama’s declaration that Syrian action on chemical weapons was a "red line" for the United States that would prompt action.
"We have made our views very clear: This is a red line for the United States," Clinton told reporters. "I’m not going to telegraph in any specifics what we would do in the event of credible evidence that the Assad regime has resorted to using chemical weapons against their own people. But suffice it to say, we are certainly planning to take action if that eventuality were to occur."
Syria said Monday it would not use chemical weapons against its own people. The Ministry of Foreign Affairs said Syria "would not use chemical weapons - if there are any - against its own people under any circumstances."
Syria has been careful never to confirm that it has any chemical weapons.
The use of chemical weapons would be a major escalation in Assad’s crackdown on his foes and would draw international condemnation. In addition to causing mass deaths and horrific injuries to survivors, the regime’s willingness to use them would alarm much of the region, particularly neighboring states, including Israel.
At the White House, press secretary Jay Carney said, "We are concerned that in an increasingly beleaguered regime, having found its escalation of violence through conventional means inadequate, might be considering the use of chemical weapons against the Syrian people. And as the president has said, any use or proliferation of chemical weapons by the Syrian regime would cross a red line for the United States. "
Administration officials would not detail what that response might be.
Although Syria is one of only seven nations that have not signed the Chemical Weapons Treaty, it is a party to the 1925 Geneva Protocol that bans the use of chemical weapons in war. That treaty was signed in the aftermath of World War I, when the effects of the use of mustard gas and other chemical agents outraged much of the world.
Clinton didn’t address the issue of the fresh activity at Syrian chemical weapons depots, but insisted that Washington would address any threat that arises.
An administration official said the trigger for U.S. action of some kind is the use of chemical weapons or movement with the intent to use or provide them to a terrorist group like Hezbollah. The U.S. is trying to determine whether the recent movement detected in Syria falls into any of those categories, the official said. The administration official was speaking on condition of anonymity this person was not authorized to speak publicly about the issue.
The senior defense official said the U.S. does not believe that any Syrian action beyond the movement of components is imminent.
An Israeli official said if there is real movement on chemical weapons, it would require a response. He didn’t say what that might be and spoke on condition of anonymity pending a formal government response to the reports of the latest activities.
Israeli officials have repeatedly expressed concerns that Syrian chemical weapons could slip into the hands of Hezbollah or other anti-Israel groups, or even be fired toward Israel in an act of desperation by Syria.
Syria is believed to have several hundred ballistic surface-to-surface missiles capable of carrying chemical warheads.
Its arsenal is a particular threat to the American allies, Turkey and Israel, and Obama singled out the threat posed by the unconventional weapons earlier this year as a potential cause for deeper U.S. involvement in Syria’s civil war. Up to now, the United States has opposed military intervention or providing arms support to Syria’s rebels for fear of further militarizing a conflict that activists say has killed more than 40,000 people since March 2011.
Clinton said that while the actions of President Bashar Assad’s government have been deplorable, chemical weapons would bring them to a new level.
"We once again issue a very strong warning to the Assad regime that their behavior is reprehensible, their actions against their own people have been tragic," she said. "But there is no doubt that there’s a line between even the horrors that they’ve already inflicted on the Syrian people and moving to what would be an internationally condemned step of utilizing their chemical weapons."
Activity has been detected before at Syrian weapons sites, believed to number several dozen.
Defense Secretary Leon Panetta said in late September the intelligence suggested the Syrian government had moved some of its chemical weapons in order to protect them. He said the U.S. believed that the main sites remained secure.
Asked Monday if they were still considered secure, Pentagon press secretary George Little declined to comment about any intelligence related to the weapons.
Senior lawmakers were notified last week that U.S. intelligence agencies had detected activity related to Syria’s chemical and biological weapons, said a U.S. intelligence official, speaking on condition of anonymity to discuss the closed-door meetings. All congressional committees with an interest in Syria, from the intelligence to the armed services committees, are now being kept informed.
"I can’t comment on these reports but I have been very concerned for some time now about Syria’s stockpiles of chemical weapons and its stocks of advanced conventional weapons like shoulder-launched anti-aircraft missiles," said House intelligence committee Chairman Mike Rogers, R-Mich. "We are not doing enough to prepare for the collapse of the Assad regime, and the dangerous vacuum it will create. Use of chemical weapons by the Assad regime would be an extremely serious escalation that would demand decisive action from the rest of the world," he added.
Syria is believed to have one of the world’s largest chemical weapons programs, and the Assad regime has said it might use the weapons against external threats, though not against Syrians. The U.S. and Jordan share the same concern about Syria’s chemical and biological weapons - that they could fall into the wrong hands should the regime in Syria collapse and lose control of them.