U.S. Defense Secretary Leon Panetta says the bombing in Damascus that killed several high-level officials on Wednesday is evidence that the situation in Syria is “rapidly spinning out of control.”

Panetta called for the international community to bring “maximum pressure” on Syrian President Bashar al-Assad to step down.

In Moscow, Russian defense minister Sergei Lavrov said Moscow cannot approve a U.N. resolution imposing sanctions on Syria because that would amount to support of a revolution.

Members of the U.N. Security Council are set to vote on the resolution and a Russian draft that does not include sanctions later Wednesday.