United Nations — Russia and China again vetoed a Western-backed U.N. resolution Thursday aimed at pressuring President Bashar Assad's government to end the escalating civil war in Syria, sparking dire warnings of even greater bloodshed and spillover to the wider region.

The 11-2 vote, with two abstentions from South Africa and Pakistan, was the third double veto of a resolution addressing the Syria crisis, now in its 17th month, by Damascus' most important allies.

The key stumbling block was the West's insistence that a new resolution include the threat of non-military sanctions to step up pressure against Assad's regime. The sanctions are under Chapter 7 of the U.N. Charter, which also includes provisions authorizing the use of force, but no force was authorized in the British draft.

Russia's U.N. Ambassador Vitaly Churkin said the resolution should never have been put to a vote because the sponsors knew it had no chance of adoption.

"We simply cannot accept a document under Chapter 7, one which would open the path for the pressure of sanctions and further to external military involvement in Syrian domestic affairs," he said.

The defeat leaves in limbo the future of the 300-strong U.N. observer mission in Syria, which was forced to suspend operations because of the intensified fighting. Its mandate, to monitor a cease-fire and implementation of international envoy Kofi Annan's six-point peace plan, expires Friday.