President Vladimir Putin is set to launch a huge military assault on the Syrian city of Aleppo, exploiting a political lull in Washington during the presidential election .
The Russian leader could launch its firepower as early as this week as he attempts to help his ally Syrian President Bashar al-Assad secure the rebel-held east of the city.
Moscow's only aircraft carrier will be used in the offensive, which threatens the lives of 275,000 people still living in the area, wester intelligence sources have revealed.
"We think the Russians are on the brink of a major military assault on Aleppo," the source told The Times.
"There could be significant humanitarian consequences."
Tens of thousands of people have already been killed by the Syrian regime and Russian forces, which have seen residential areas, schools and hospitals destroyed.
Syria's civil war pits President Assad, backed by Iran and Shi'ite Muslim militias from Lebanon, Iraq and Afghanistan against an array of mostly Sunni rebel groups, including some backed by Turkey, Gulf monarchies and the US.
Idlib, near Aleppo in north-west Syria, contains the largest populated area controlled by rebels, both nationalist groups under the banner of the Free Syrian Army and Islamist ones including the former al Qaeda affiliate Jabhat Fateh al-Sham.
The high death toll from strikes by the Syrian military and Russian air force in rebel-held areas has prompted criticism from Western countries and international human rights groups.