BEIRUT -- Syria's President Bashar Assad defied mounting international pressure to end the year-old crackdown on an uprising against him and said yesterday he was determined to go on fighting what he called "foreign-backed terrorism."

A day after Sen. John McCain called for airstrikes on Syria, President Barack Obama said unilateral U.S. military action against Assad's regime would be a mistake.

The United States said it is proposing a new UN Security Council resolution demanding an end to violence in Syria, first by government forces and then by opposition fighters. Russia and China, which have blocked a Security Council resolution against Syria, made it clear they were still standing by the regime in Damascus.

"The Syrian people, who have in the past managed to crush foreign plots . . . have again proven their ability to defend the nation and to build a new Syria through their determination to pursue reforms while confronting foreign-backed terrorism," Assad said, according to state news agency SANA.

The military crackdown has turned to southern Daraa province, where the uprising began a year ago. Troops shelled a village in Daraa and clashed with military defectors.

Activists said the military blasted a bridge and a tunnel near the border with Lebanon used as escape routes for the wounded and refugees fleeing central Homs province.

Rupert Colville, spokesman for the UN High Commissioner for Human Rights in Geneva, described video that has emerged of torture victims allegedly shot secretly in the Military Hospital in Homs as "truly shocking."

The video, broadcast ton Britain's Channel 4, shows wounded civilians blindfolded and chained to their hospital beds, some of them with clear torture marks on their bodies, allegedly at the hands of medical staff.

McCain, in calling for airstrikes against Syria, said the United States has a moral and strategic obligation to force out Assad and his loyalists.

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