The U.S. ambassador to the United Nations strongly condemned Russia and China on Monday for vetoing a resolution over the weekend calling on Syrian leader Bashar al-Assad to step down.
"They put a stake in the heart of efforts to resolve this conflict peacefully," Susan Rice said on CNN. "The tragedy is for the people of Syria. We the United States stand with the people of Syria. Russia and China are obviously with Assad."
Russia and China were the only two members of the U.N. Security Council to vote against the resolution, which was based on a peace plan from the Arab League. Rice said the two countries "sent mixed signals" regarding their positions leading up to the vote, and said the vote was held in part to confront Russia's "delaying tactics."
"Russia and China will, I think, come to regret this action," Rice continued. "They have by their actions by their veto dramatically increased the risk of greater violence, and you've seen manifestations of that."
Syrian troops reportedly killed more than 200 people over the weekend in the city of Homs.
President Obama condemned the violence, as well as Assad's leadership, on Saturday. “Assad must halt his campaign of killing and crimes against his own people now. He must step aside and allow a democratic transition to proceed immediately," he said in a statement.
Rice said the U.S. has "a whole range of steps, diplomatic and otherwise" for dealing with Assad without the U.N. resolution.
However, she sidestepped questions about military options.
"I don't want to get into speculation, but I do know that our aim throughout has been to use diplomacy, sanctions and economic pressure to make it absolutely clear to Assad that his days are numbered," she said.