On Monday, Former Russian President Dmitry Medvedev said that any encroachment by NATO members on the Crimean Peninsula could constitute a war against Russia, which could lead to a “third world war”.

“For us, Crimea is part of Russia. It means forever. Any attempt to invade Crimea is a declaration of war on our country,” Medvedev told the media.

“If NATO members did this, it would mean a conflict with the entire North Atlantic alliance; a third world war. A total catastrophe.”

Medvedev, now deputy chairman of the Russian Security Council, also said that if Finland and Sweden joined NATO, Russia would strengthen its borders and be prepared to take retaliatory measures, which could include installing Iskander hypersonic missiles on their threshold.