President Barack Obama on Saturday accused Syrian President Bashar al-Assad's government of murdering civilians in an "unspeakable assault" in the city of Homs, and demanded that Assad step down.
"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," Obama said in a statement.
The president's blunt condemnation came amid reports that more than 200 civilians were killed in a night of shelling by Syrian forces of residential areas in the flashpoint city of Homs.
The UN Security Council was preparing to meet on a draft resolution condemning the Assad regime and endorsing an Arab League plan for a political transition, while Russia's foreign minister planned to meet the Syrian leader in Damascus next week.
"Yesterday the Syrian government murdered hundreds of Syrian citizens, including women and children, in Homs through shelling and other indiscriminate violence, and Syrian forces continue to prevent hundreds of injured civilians from seeking medical help," Obama said.
"I strongly condemn the Syrian government's unspeakable assault against the people of Homs and I offer my deepest sympathy to those who have lost loved ones," he said.
He said the UN Security Council "now has an opportunity to stand against the Assad regime's relentless brutality and to demonstrate that it is a credible advocate for the universal rights that are written into the UN Charter."