Updated

WASHINGTON -- The White House says Syrian President Bashar Assad has "lost legitimacy" and is "not indispensible."

Spokesman Jay Carney's statement was the first time the White House has used such strong language to describe Assad's regime. His words echoed a similar statement from Secretary of State Hillary Rodham Clinton on Monday.

The rhetorical uptick from the U.S. follows an attack on the U.S. Embassy and the American ambassador's residence Monday in Damascus.

Carney says those who attacked the embassy are "thugs" and it was the Syrian government's responsibility to protect the U.S. diplomatic mission.