Russia and China vetoed a new U.N. Security Council resolution Thursday that would have imposed new sanctions on the Syrian regime.

Western countries have been pushing for a resolution that threatens sanctions against the regime of President Bashar al-Assad if government forces don't stop attacks.

However, Russia has opposed any international effort that would blame, punish or change the leadership of the Syrian government. Russia and China have vetoed two previous draft resolutions in the U.N. Security Council, leading to accusations that Russia is protecting the Syrian regime.

The resolution also calls for renewing the 300-member U.N. observer mission for 45 days after it was suspended because of violence.

Russia has put forward its own draft, which "strongly urges all parties in Syria to cease immediately all armed violence in all its forms."

U.S. President Barack Obama called his Russian counterpart, Vladimir Putin, to discuss the Syrian situation, the White House said in a statement Wednesday.

"They noted the differences our governments have had on Syria, but agreed to have their teams continue to work toward a solution," it said.