Islamic State (Isis) urged Muslims to launch a "holy war" against Russians and Americans in an audio recording distributed online. The call comes as both countries are now involved in military campaigns in the Middle East.
"Islamic youth everywhere, ignite jihad against the Russians and the Americans in their Crusaders' war against Muslims," the speech by IS spokesman Abu Mohammad al-Adnani said, reports Reuters.
The announcement comes after Russia launched air strikes in support of the forces of Syrian president Bashar al-Assad in Syria. The US has accused Russia of chiefly targeting other rebel groups, including US-backed moderate rebels, a charge Moscow denies.
On 13 October, Russian security services announced that they had foiled a plot by terrorists trained in IS camps in Syria to launch terror attacks on Moscow's public transport system.
A US-led coalition has targeted IS positions in both Syria and Iraq since September 2014. Last week, the Iraqi government said it had entered an intelligence sharing agreement with Russia and Iran in the campaign against IS.
The message also confirmed the death of Abu Mutaz Qarashi, a senior IS commander. Eight senior figures from IS were killed in an Iraqi airstrike in Iraq on 11 October, the Iraqi military said.