Admiral Radakin, the UK’s chief of defence staff, said Russia was under pressure because “it’s running out of people and it’s running out of high-tech missiles”.
Russia has “strategically lost” the war in Ukraine and is a “more diminished power”, the head of the UK’s armed forces has said.
Admiral Sir Tony Radakin said Vladimir Putin had lost 25% of Russia’s land power for only “tiny” gains.
And while Russia may achieve “tactical successes” in the coming weeks, he said any notion the war had been a success was “nonsense”.
Admiral Radakin said: “This is a dreadful mistake by Russia. Russia will never take control of Ukraine.
“Russia has strategically lost already. NATO is stronger, Finland and Sweden are looking to join.”
He said Moscow had been forced to give up its objectives of taking over most Ukrainian cities and was now engaged in a tactical battle where fighting is “tough”.
Admiral Radakin said: “The Russian machine is grinding away, and it’s gaining a couple of – two, three, five – kilometres every day.
“And that’s tough for Ukraine, but this is going to be a long fight. And we’re supporting Ukraine, Ukraine has shown how courageous it really is.
“And Russia has vulnerabilities because it’s running out of people, it’s running out of hi-tech missiles.”
He continued: “President Putin has used about 25% of his army’s power to gain a tiny amount of territory and 50,000 people either dead or injured.”
Russia is now a “more diminished power” diplomatically and economically than several months ago, he said.
“Any notion that this is a success for Russia is nonsense. Russia is failing.
“It might be getting some tactical successes over the last few weeks. And those might continue for the next few weeks.
“But Russia is losing strategically.”