Russia's parliament has ratified a treaty with Damascus that allows Russian troops to stay indefinitely in Syria.
Ratification of the treaty on October 7 came as Russian warplanes continued to support a Syrian offensive against rebel-held parts of Aleppo, where more than 250,000 civilians are stranded.
Since the collapse of a U.S.-Russia-brokered cease-fire on September 19, ties between Moscow and Washington have become increasingly strained.
Meanwhile, Russia has been bolstering its forces with the deployment of antiaircraft missile systems, cruise missiles, warships, and additional troops.
Russia's United Nations ambassador Vitaly Churkin has rejected a French-proposed Security Council resolution that would call for grounding all aircraft, including Russia's, over Aleppo.
The resolution, which also calls for an Aleppo cease-fire, is to be considered by the council on October 8, but Churkin has said he “cannot possibly see how” Russia could let the resolution pass.