Narciso Contreras/Associated Press
WASHINGTON — President Obama warned Syria on Monday not to use chemical weapons against its own people, vowing to hold accountable anyone who did, even as American intelligence officials picked up signs that such arms might be deployed in the fighting there.
The White House said it had an “increased concern” that the government of President Bashar al-Assad was preparing to use such weapons, effectively confirming earlier reports of activity at chemical weapons sites. The administration said it would take action if they were used, suggesting even the possibility of military force.
“Today I want to make it absolutely clear to Assad and those under his command: The world is watching,” Mr. Obama said in a speech at the National Defense University in Washington. “The use of chemical weapons is and would be totally unacceptable. If you make the tragic mistake of using these weapons, there will be consequences and you will be held accountable.”
Neither the president nor his aides would specify how it would hold Syrians accountable, but the White House confirmed that contingency plans had been drawn for direct action. The president’s statement amplified similar warnings issued by Secretary of State Hillary Rodham Clinton earlier in the day in Prague, the capital of the Czech Republic, which represents the interests of the United States in Damascus now that the American Embassy there has been closed.
“This is a red line for the United States,” Mrs. Clinton said. “I am 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.”
The sharpening language came as NATO was preparing to buttress its member Turkey against a potential attack from Syria. A plan expected to be endorsed by the alliance’s foreign ministers during two-days of meetings that begin Tuesday in Brussels calls for deploying American, German and Dutch Patriot missile-defense batteries under the operational control of the NATO military command, Western officials said Monday.
Such a move would be the most direct action in the Syrian conflict by the alliance, which has remained cautious about intervention there. But for months, Turkey has expressed concerns about the potential of missile attacks from Syria as relations between the two countries have worsened, and last month Ankara asked for Patriot batteries.
As the United States and its allies tried to forestall the conflict from escalating, the Syrian Foreign Ministry said the government “would not use chemical weapons, if it had them, against its own people under any circumstances.” The statement was reported on Syrian state television and on the Lebanese channel LBC.
Mr. Obama has called for Mr. Assad to step down but has shied away from taking direct action sought by Syrian rebels. With the election over, advisers are considering a more robust response, including possibly providing arms to the rebels and recognizing the opposition as the legitimate representative of the Syrian people.
But Mr. Obama avoided any mention of such actions in his speech. “We will work to support the legitimate aspirations of the Syrian people, engaging with the opposition, providing them with the humanitarian aid and working for a transition to a Syria that’s free of the Assad regime,” he said.
Jay Carney, the president’s press secretary, hinted at possible military action in response to any use of chemical weapons but declined to specify options. “We think it is important to prepare for all scenarios,” he said. “Contingency planning is the responsible thing to do.”
Mrs. Clinton flew from Prague to Brussels for the NATO meeting. A senior NATO official said the alliance would declare its support for Turkey’s request for help and welcome the intention of three allied nations to deploy Patriot missile batteries there. It would then be up to the United States, Germany and the Netherlands to decide how many batteries to deploy and for how long.
Surveys are being conducted of 10 potential sites, mainly in southeastern Turkey, but a senior American official traveling with Mrs. Clinton said it would probably take several weeks to deploy the batteries. Once deployed, they would be under the operational control of NATO’s top military commander, Adm. James. G. Stavridis.
The pending move has prompted speculation that it might be an indirect way of extending protection to forces opposing Mr. Assad in northern Syria by targeting Syrian warplanes operating there. But NATO and American officials were adamant that was not the purpose.
“There is no safe haven,” the American official with Mrs. Clinton said. “There is no de facto cross-border aspect to this.”
Instead, officials said the idea was to discourage Syria from threatening Turkey for supporting Syrian insurgents — and to discourage Turkey from feeling pressured to intervene to head off attacks against it. The Turkish military issued a statement Monday calling the deployment “a measure entirely aimed at defense.”