President Barack Obama said in a nationally televised address Tuesday night that recent diplomatic steps offer "the potential to remove the threat of chemical weapons" inside Syria without the use of force, but he also insisted the U.S. military will keep the pressure on President Bashar Assad "and be ready to respond" if other measures fail.

Speaking from the East Room of the White House, Obama said he had asked congressional leaders to postpone a vote on legislation he has been seeking to authorize the use of military force against Syria.

Acknowledging the weariness the nation feels after a decade of war in Iraq and Afghanistan, Obama said, "America is not the world's policeman."

And yet, he added, "When with modest effort and risk we can stop children from being gassed to death and thereby make our own children safer over the long run, I believe we should act. That's what makes America different. That's what makes us exceptional."

Administration officials said the speech was the sixth Obama has made to the nation from the White House in more than 4 ½ years as president. It capped a frenzied 10-day stretch that began when he unexpectedly announced he was stepping back from a threatened military strike and asking Congress to pass legislation authorizing the use of force against Assad.

With public opinion polls consistently showing widespread opposition to American military intervention, the White House has struggled mightily to generate support among lawmakers - liberal Democrats and conservative Republicans alike - who have expressed fears of involvement in yet another war in the Middle East and have questioned whether U.S. national security interests were at stake in Syria. Obama had trouble, as well, building international support for a military attack designed to degrade Assad's military.

Suddenly, though, events took another unexpected turn on Monday. First Russia and then Syria reacted positively to a seemingly off-hand remark from Secretary of State John Kerry indicating that the crisis could be defused if Damascus agreed to put its chemical weapons under international control.