Cautious response to Russia's humanitarian corridors into Aleppo

Russia has announced it's working with the Syrian government to open up routes giving civilians a way out of the besieged city of Aleppo. Russia's defence minister says three humanitarian corridors will be opened, while there'll be a fourth for any rebel fighters willing to surrender. But the US has responded to the announcement with caution.

Russian Defence Minister Sergei Shoigu Source: AAP