Western and Arab states voiced outrage after Russia and China vetoed a U.N. resolution that would have backed an Arab plan urging Syrian President Bashar al-Assad to give up power, and Washington vowed to impose harsher sanctions against Damascus. U.S. Secretary of State Hillary Clinton called the veto a "travesty." It came a day after activists said that Syrian forces had bombarded a district of Homs, killing more than 200 people in the worst night of bloodshed of the 11-month uprising. Russia said the resolution was biased and would have meant taking sides in a civil war. Syria is Moscow's only major ally in the Middle East, home to a Russian naval base and a customer for its arms. China's veto appeared to follow Russia's lead.