The United States and its allies are trying to stop the civil war in Syria and get rid of Syrian President Bashir Bashar al-Assad.
But to do that, they need the approval of key members of the United Nations Security Council, including Russia.
As the Syrian army rolls into rebel strongholds around Damascus, trying to crush a ten-month-old rebellion, world leaders at the U.N. are pressuring Russia to go along with a draft resolution demanding that Assad relinquish power and stop what the U.S. calls brutal attacks by the government against its own people.
"We all have a choice: Stand with the people of Syria and the region or become complicit in the continuing violence there," U.S. Secretary of State Hillary Clinton said.
"Syria belongs to its 23 million citizens, not to one man or his family. And change can still be accomplished without dismantling the state or producing new tyranny," she said.
Russia, one of Assad's strongest allies, said it will veto any U.N. action against Damascus. The Russians are afraid any action could open the door to eventual international military involvement, the way an Arab-backed U.N. resolution led to NATO air strikes in Libya.
"Russia would not support anything that would be actually imposed on Syrians," Russian Foreign Minister Sergey Lavrov said.
Russia said the rest of the world should stay out of it and that removing Assad would lead to a civil war.
But French Foreign Minister Alain Juppe said Assad "has blood on his hands."
U.S. Intelligence Director Jim Clapper and CIA Director David Petraeus told Congress the dictator's days are numbered.
"I personally believe it's a question of time before Assad falls," Clapper said.
Diplomats who make up the U.N. Security Council are expected to debate again Wednesday on how to handle the continuing crisis.