HARRISBURG - Sen. Bob Casey is urging strong action in Syria now that the White House says it has conclusive evidence that Syrian President Bashar Assad's regime has used chemical weapons against opposition forces.
A Thursday statement from Casey reminds President Barack Obama that using chemical weapons has crossed a "red line" that Obama has said would trigger greater American involvement in the crisis.
Casey says Assad must go, but that it won't happen without decisive American leadership.
Casey says he spoke Wednesday with the Syrian opposition's military leader and fears that moderate opposition forces will be defeated without U.S. intervention.
He says Obama should consider grounding the Syrian air force with stand-off weapons and using Patriot missiles in Turkey to protect a safe zone in northern Syria.