Russia faces UN showdown over Aleppo siege

International pressure on Moscow to end the joint siege of Aleppo is growing as Russia faces a key United Nations vote over the siege of the Syrian city.

Moscow's UN ambassador says he will most likely veto a Security Council resolution that would ground Russian warplanes as Russia's parliament ratified a treaty with Syria that allows its troops to stay indefinitely in the country - a show of support for embattled President Bashar Assad.