Isis has released a video showing a Russian-speaking man 'confessing' to working as a spy before being beheaded.
The video, which has not been authenticated, shows a bearded man speaking from a chair.
He says he is a Chechen man called Magomed Khasayev and was sent to Isis-controlled territory by Russian intelligence services to spy on fighters who will potentially return home to carry out attacks.
The video then shifts to show him kneeling beside a knife-wielding jihadist, who addresses President Vladimir Putin in Russian calling him a "dog".
He says Russians will be killed in retaliation for the country’s air strikes.
Russia began air strikes against Isis and other rebel groups in Syria on 30th September after being invited by President Bashar al-Assad.
The video follows the bombing of a Russian passenger jet shortly after it took from the Egyptian resort of Sharm el-Sheikh in mid-October, killing all 224 people on board.
In an audio message, an Isis affiliate in the Sinai Peninsula where the plane came down claimed responsibility for the attack.
They said: "We downed it, so die in your rage".
It comes just hours after the UK Parliament voted to approve air strikes against the terrorist group.
The RAF is believed to have struck six Isis-controlled targets overnight.
Additional reporting by AP