The American President has said the US will do everything it can to make a truce in Syria succeed - despite significant concerns over whether the agreement will hold.
The United States, Russia and other parties have agreed to a pause in hostilities in the country - which is due to begin later.
Barack Obama has said maintaining the deal would depend on a number of factors: “Humanitarian aid must be allowed to reach areas under siege.
“And a lot of that is going to depend on whether the Syrian regime, Russia and their allies, live up to their commitments.
“The coming days will be critical and the world will be watching.”