The White House says the United States is increasingly concerned about Syria's intentions regarding the use of chemical weapons.
White House spokesman Jay Carney said Washington is preparing contingency plans.
Carney declined to say what the contingency plans involved.
His comments came after Secretary of State Hillary Clinton warned that the United States would take action if Syria used the weapons.
Clinton, speaking in Prague, said the use of chemical weapons by President Bashar al-Assad's regime was a "red line" that would prompt action.
Syria's government reacted to Clinton's warning, saying it would "never, under any circumstances" use chemical weapons against its own people.
Meanwhile, the United Nations says it is withdrawing "all nonessential international staff" from Syria due to the deteriorating security situation.
Based on reporting by AFP, Reuters, and AP