Prime Minister Shinzo Abe and U.S. President Barack Obama confirmed over the phone Tuesday their countries will cooperate over the Syrian conflict as Obama continued efforts to gain congressional support for a military strike against President Bashar Assad's regime over its alleged use of chemical weapons.

During the 30-minute conversation initiated by Washington, the two leaders also confirmed that, based on humanitarian grounds, the use of chemical weapons cannot be condoned under any circumstances.

Obama hopes to gain congressional approval for a possible U.S. strike against Assad's government over its apparent use of nerve gas, apparently sarin, on the outskirts of Damascus on Aug. 21. TV footage apparently showed victims of the gassing, some in convulsions.