The Chief of the Defence Staff has said that Vladimir Putin is "failing on all of his military strategic objectives" as the war in Ukraine continues.
Admiral Sir Tony Radakin was asked about the situation in Ukraine and told BBC's Sunday With Laura Kuenssberg programme: "At the very outset, we said that this was a strategic error by President Putin and strategic errors lead to strategic consequences.
"And in this instance, it's strategic failure. Putin is failing on all of his military strategic objectives, he wanted to subjugate Ukraine, that's not going to happen."
Putin's "under pressure, his problems are mounting"
The CDS added: "He (Putin) wanted to take control of the capital, we saw that that was defeated earlier on. We saw that he wanted to weaken NATO. NATO is now much stronger, and we have Finland and Sweden joining.
"He wants to break the international resolve. Well, actually that strengthened over this period, and he's under pressure, his problems are mounting.
"He's always had a problem in terms of crewing the equipment that he's got. He hasn't got sufficient manpower. His forces are thin on the ground. And we're also seeing a magnificent Ukrainian armed forces who have been courageous, they're fighting for their country, and they've embraced the international support that all of us are providing."
Watch: Former Royal Marine and documentary-maker Emile Ghessen told Forces News the Ukrainian's "morale is very high, there's lots of talks of victory before winter".
"People need to be cautious"
Admiral Radakin did however highlight that the conflict in Ukraine is likely to "grind on for a long time" and that "we've got to be very cautious".
"I think it’s significant in terms of what's happening on the ground it's really significant for Ukrainian morale and significant for the impact it has on Russian forces", he said.
"But people need to be cautious, the likely result with all of this is that it's going to grind on for a long time.
"And that's why there's a wishfulness when people jump to conclusions that either President Putin is weak and his power base might be undermined, or that Ukraine has gained some ground and there's been a magnificent action in the northeast.
"But it doesn't automatically lead on to easy victories elsewhere."
Russian shelling hit cities and towns across a wide stretch of Ukraine during the night, officials have said.
The Ministry of Defence (MOD) has warned that Russia is likely to increase its attacks on civilian targets as it suffers battlefield defeats.
"In the last seven days, Russia has increased its targeting of civilian infrastructure even where it probably perceives no immediate military effect," the MOD said in an online briefing.
"As it faces setbacks on the front lines, Russia has likely extended the locations it is prepared to strike in an attempt to directly undermine the morale of the Ukrainian people and government."