The Russian invasion of Ukraine has been described as a "rehearsal" for a world war by an analyst on the country's state TV.
Professor Alexei Fenenko, a leading research fellow at the Institute of International Security Studies, signalled on the state-controlled channel Russia-1 that a future conflict could be with The North Atlantic Treaty Organisation (Nato).
Speaking on a discussion panel this week, Prof Fenenko used the term "war" - as opposed to the Kremlin's insistence that the Ukraine invasion was a "special military operation" - and suggested more was to come.
He said: "For us, the war in Ukraine is a rehearsal. Rehearsal for a possible bigger conflict in the future. We'll test and compare Nato weapons to our own, we'll find out on the battlefield how much stronger our weapons are then theirs. This may be a learning experience for future conflicts."
Speaking on Twitter, retired US general Barry R McCaffery described Prof Fenenko's statement as "astonishing" given how much stronger Nato was compared to Russia.
He said: "The economic and conventional military power of Nato/EU is multiple times that of Russia. A rehearsal for a war with Nato against a much smaller adversary in Ukraine that’s going very badly for Russia. Escalation of Russian aggression against other Nato countries would be completely illogical."
Prof Fenenko's comments came after both Sweden and Finland applied to join Nato, a grouping of 30 member states. Russian president Vladimir Putin said on Monday that an expansion of the alliance into either country would force Moscow to react.
It came as Russia said it had "completely liberated" the Azovstal steel plant in the Ukrainian coastal city of Mariupol. Nearly 1,000 Ukrainian soldiers reportedly left the steelworks early this week after a siege lasting 80 days.
Major General Igor Konashenkov, a spokesman for the Russian Defence Ministry said: "The territory of the Azovstal metallurgical plant in Mariupol, where since April 21 the group of Ukrainian militants of the Azov Nazi formation has been blocked, has been completely liberated."
The Ukrainian captives are being taken to a Russian prison colony. There are fears that Russian president Vladimir Putin could put them on trial as “Nazi war criminals”.
A small resistance force in and around the four square-mile steelworks was all that remained and it is believed they have also been defeated.
