U.S. President Barack Obama said on Thursday the United States would do everything it could to make a ceasefire in Syria succeed despite significant question marks over whether the agreement will hold. The United States, Russia and other parties have agreed to a "cessation of hostilities" in Syria that is set to begin Saturday from midnight. After a meeting with his national security team at the State Department, Obama expressed U.S. resolve to try to make the deal work but cautioned there were reasons for skepticism.