Syrian human rights groups say at least 50 people were killed on Monday morning when Syrian forces bombarded the western Syrian city of Homs.

Homs has been a center of antigovernment protests during Syria’s eleven-month uprising.

Western countries have renewed efforts to put pressure on Syria after China and Russia vetoed a U.N. Security Council resolution condemning the Syrian government's bloody crackdown on antigovernment protests.

The United States shut down its embassy in Syria and pulled out all of its diplomats.

The U.S. is reportedly planning to promote international cooperation for the expulsion of Syria’s government while ruling out the possibility of taking military action.

The British government, on its part, summoned its ambassador to Syria while the leaders of Germany and France strongly denounced China and Russia for vetoing the U.N. Security Council resolution concerning Syria.