The Obama administration is hailing what it calls the "first major diplomatic defection" from the regime of Bashar Assad in Syria.

The Syrian ambassador to Iraq, Nawaf Fares, has announced that he's joining the opposition to Assad. He told the Al-Jazeera satellite channel today that the only thing that will drive Assad from power is the use of force. Fares says Assad will delay or ignore any international peace plan.

In Washington, State Department spokesman Patrick Ventrell said the defection is "a wider sign that the regime is feeling the pressure" and "starting to fall apart."

Fares is the second prominent Syrian to break with the regime in less than a week. A brigadier general (Manaf Tlass) defected last week, but hasn't spoken publicly.