Obama cautious on Syria plan as opposition yet to commit

By Jeff Mason and Tom Perry WASHINGTON/BEIRUT (Reuters) - U.S. President Barack Obama expressed caution on Wednesday about a plan to stop fighting in Syria, while the main opposition group said it had yet to commit to the deal. Combatants are required to say whether they will agree to the "cessation of hostilities" by noon on Friday (1000 GMT), and to halt fighting at midnight Saturday. The United Nations hopes the planned halt in the fighting will provide a breathing space for Syrian peace talk