Mr. Obama appeared to be trying to keep the promise on which he was elected, to avoid repeating the mistakes of the American invasion of Iraq by limiting the scope of the strike and seeking consensus.

http://www.nytimes.com/2013/09/01/world/middleeast/for-syrians-obamas-decision-to-seek-approval-first-lengthens-suspense-of-attack.html?hp&_r=0