NATO encroachment on Crimea could lead to World War III, warns Russia's Medvedev

"For us, Crimea is a part of Russia. And that means forever. Any attempt to encroach on Crimea is a declaration of war against our country," Medvedev told the news website Argumenty I Fakty, a weekly newspaper based in Moscow, Monday.

"And if this is done by a NATO member-state, this means conflict with the entire North Atlantic alliance; a World War Three. A complete catastrophe," he added.

Medvedev also said that if Finland and Sweden joined NATO, Russia would strengthen its borders and would be "ready for retaliatory steps," and that could include the prospect of installing Iskander hypersonic missiles "on their threshold."

Last week, the head of pro-Russian forces in the Crimean Peninsula said Kiev forces had targeted oil drilling platforms in the Black Sea, amid Russia’s months-long special operation in the former Soviet republic.

The head of pro-Russian forces in the Crimean Peninsula accuses the Ukrainian government troops of attacking oil drilling platforms in the Black Sea.

Sergei Askyonov said in a post on his Telegram account that the Ukrainian forces had launched missile attacks on drilling platforms of Chernomorneftegaz energy company in the Black Sea and off the coast of Crimea.

The Ukrainian strike against an offshore energy infrastructure in Crimea, which rejoined Russia in a 2014 referendum, is the first reported such attack since the start of Moscow's military operation in eastern Ukraine in late February.

Since Crimea rejoined Russia, Ukraine, the United States and the European Union have refused to recognize the Black Sea peninsula as part of Russian territory, and imposed sanctions against Moscow.