The absence of any large scale mobilisation of NATO forces in Europe is indicative enough of this being alarmism. Any strategic offensive against NATO would risk a nuclear exchange which Putin would never risk. Not to mention their ageing fleet and smoke-belching aircraft carrier would lucky to even make it to the Adriatic without breaking down.

In terms of likelihood, first on the list would be this is just another case of Putin sabre-rattling to bully NATO into favourable terms over Ukraine.

If Russia does invade, it will be at enormous cost economically and militarily. Ukraine has a fairly credible air defence network and now has an unknown quantity of British-supplied anti-tank weaponry. They won't be able to win the fight outright but they can make it so costly that it isn't worth it to continue.

The oligarchs will find their Swiss bank accounts frozen and their assets seized, Aeroflit might be banned from NATO aligned nations, the UN will impose sanctions. They'll be so fucked the Russian people will get rid of Putin for us.