U.S., Russia set for surprise Syria meeting

Should a plan similar to that one be proposed, the Obama administration is likely to insist anew that it be internationally enforceable — a step Moscow may still be reluctant to commit to.

In any case, the U.S. insists the tide of the war is turning definitively against Assad.

On Wednesday, the administration said several countries in the Middle East and elsewhere have informally offered to grant asylum to Assad and his family if they leave Syria.

The comments came a day after the United States and its 27 NATO allies agreed to send Patriot missiles to Turkey's southern border with Syria. The deployment, expected within weeks, is meant solely as a defensive measure against the cross-border mortar rounds from Syria that have killed five Turks, but still bring the alliance to the brink of involvement in the civil war.

The United States is also preparing to designate Jabhat al-Nusra, a Syrian rebel group with alleged ties to al-Qaida, as a foreign terrorist organization in a step aimed at blunting the influence of extremists within the Syrian opposition, officials said Wednesday.

Word of the move came as the State Department announced Clinton will travel to the Mideast and North Africa next week for high-level meetings on the situation in Syria and broader counter-terrorism issues. She is likely then to recognize Syria's newly formed opposition coalition as the legitimate representative of the Syrian people, according to officials.

The political endorsement is designed to help unite the country against Assad and spur greater nonlethal and humanitarian assistance from the United States to the rebels.