Did Putin threaten to go nuclear on ISIS?

Vladimir Putin has warned that a new underwater missile system deployed by Russian submarines in the war against ISIS in Syria could be equipped with nuclear warheads.

The Russian president said that although using nuclear weapons was a possibility, he hoped that they would 'never be needed' in the fight against terrorism. 

His warning came as Russia stepped up its barrage on Syrian rebels with its first submarine-launched cruise missile strikes combined with bombing raids from the air.

Speaking on Russian state television today, Putin claimed his military had struck '300 targets of different kinds' in the past three days and helped Syrian special forces recover the black box of a Russian warplane downed by Turkey last month.

President Putin said the cruise missiles, launched from the submarine in the Caspian Sea, could be equipped with nuclear warheads but said he hoped they would 'never be needed in the fight against terrorism'.

'With regard to strikes from a submarine: we certainly need to analyse everything that is happening on the battlefield, how the weapons work. Both the [Kalibr] missiles and the Kh-101 rockets are generally showing very good results. We now see that these are new, modern and highly effective high-precision weapons that can be equipped either with conventional or special nuclear warheads.'

'Naturally, we do not need that in fighting terrorists, and I hope we will never need it. But overall, this speaks to our significant progress in terms of improving weaponry and equipment being supplied to the Russian army and navy.'