During the 2008 presidential campaign, both Barack Obama and Joe Biden made it completely clear that the president could not authorize a military strike without congressional approval except for a case of an “imminent threat" to the American people. Syria poses no imminent threat to national security.
The President does not have power under the Constitution to unilaterally authorize a military attack in a situation that does not involve stopping an actual or imminent threat to the nation. -Barack Obama
Be true to what you have said and do not start without the democratic approval of Congress and the American people.