But at the same time in a nationally-televised address from the from the White House Tuesday night, Obama also made a forceful case for why the US must retaliate against Syrian president Bashar al-Assad regime's alleged use of chemical weapons if diplomacy fails.

"If we fail to act, the Assad regime will see no reason to stop using chemical weapons," he said. "The purpose of a strike would be to deter Assad from using chemical weapons and make clear to the world we will not tolerate their use."