In a statement Obama said that if the regime of President Bashar al-Assad does not live up to the deal Washington reached with Syria's ally Russia, "the United States remains prepared to act."
Amid questions about how the deal would be enforced should Syria fail to live up to its obligations, Obama said the United States would work with Russia, Britain, France and the United Nations to ensure there are consequences.
Much work remains to be done, he said. And if diplomacy fails on Syria, "the United States remains prepared to act," he said.
The Pentagon said on Saturday that US military forces were still positioned for possible military strikes on Syria, at least for now, even after a Russia-US agreement on destroying Syria's chemical weapons arsenal.
"We haven't made any changes to our force posture to this point," Pentagon spokesman George Little said in a statement.
"The credible threat of military force has been key to driving diplomatic progress, and it's important that the Assad regime lives up to its obligations under the framework agreement."
Voice of Russia, AFP, Reuters