President Obama said it was the credible U.S. military threat against Syria that led to a possible diplomatic solution to the crisis.
The president referred to Syria's agreement to a Russian proposal to put its chemical weapons under international control and have them destroyed.
Mr. Obama said it is too early to tell if such a deal will work, but he said it is the chance to avoid the use of force.
He said he has asked Congress to postpone votes on a military strike, and said he will continue his contacts with Russian President Vladimir Putin.
But Mr. Obama said he has asked the U.S. military to maintain its current posture and keep pressure on the Assad regime.