"The idea of joining Russia is still popular in Abkhazia and South Ossetia," Medvedev, a former Russian president, wrote in an article.
Former president and current deputy chairman of Russia's Security Council, Dimitry Medvedev, said that Russia would be forced to use nuclear weapons if Ukraine's counter-offensive succeeds.
"The completely crazy West could not come up with anything else... In fact, it's a dead end. World War Three is getting closer," Medvedev wrote on the Telegram messaging app.
Medvedev, deputy chairman of Russia's Security Council, said the whole world would be on the brink of catastrophe if Russian nuclear weapons fell into the hands of "bandits".
Ex-President Medvedev suggests that Polish President Andrzej Duda should be dragged to Red Square and executed via quartering.
Russia, which has more nuclear weapons than any other state, has repeatedly said the West is engaged in a proxy war with Russia over Ukraine that could escalate into a much bigger conflict.
The United States has committed $37 billion in security assistance to Ukraine since Putin sent troops into Ukraine in February last year.
Dmitry Medvedev: "In place of the American military, I would immediately make a fake trunk with false nuclear codes in case he wins, so as to avoid fatal consequences."
Medvedev listed why countries from every continent do not need Ukraine to exist, calling on the memory of emotive historic and modern day conflicts and injustices to justify his perception.
Dmitry Medvedev: "One does not negotiate with terrorists. They are exterminated as rabid dogs, poisonous saliva flowing from their mouths."