Kerry issues warning as Syrian parties back halt to fighting

By Tom Perry and Patricia Zengerle BEIRUT/WASHINGTON (Reuters) - The government of Syrian President Bashar al-Assad and rebel groups have accepted a plan for a cessation of hostilities to begin on Saturday and the United States warned it would be hard to hold the country together if the fighting does not stop. With hostilities reported on several fronts, rebels backed by Saudi Arabia expressed doubts about the proposal, which excludes attacks by the Syrian army and its Russian backers on the jih