Obama: Use of chemical weapons would change my calculus

US President Barack Obama said Friday the use of chemical weapons would change the rules of the game, but added, “Knowing that there’s chemical weapons in Syria doesn’t tell us when they were used or how. We ourselves will be putting a lot of resources on this. We and the world could not stand by and permit the systematic use of weapons like chemical weapons on civilian populations.”

Speaking at the White House Friday alongside Jordan’s King Abdullah, Obama then hedged. “A line has been crossed,” he said, “when we are seeing tens of thousands of killed by the regime. For the Syrian government to use chemical weapons against its people would change my calculus. This is not an on and off switch, it’s an ongoing challenge…”