Ukraine is preparing carefully for a new counter-offensive against Russian forces because the assault is "very important" and must "demonstrate success", the prime minister has said.
Denys Shmyhal told Sky News that the long-awaited operation would only be launched when the time is right but he gave no indication when that might be.
With Russian President Vladimir Putin on Tuesday commemorating Victory Day – marking the Soviet Union's defeat of Nazi Germany in the Second World War – the Ukrainian prime minister said the most important day for Kyiv will be when it defeats Russia's invasion.
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"I'm sure that the most important victory day for Ukraine will be victory day over this terrible Russian aggression – full-scale aggression – against Ukraine," he said, speaking during a trip to the UK to attend the coronation of King Charles.
Mr Shmyhal visited a British military training area on Salisbury Plain to watch British and New Zealand troops helping to train Ukrainian recruits as part of a British-led assistance programme to turn thousands of Ukrainian civilians into soldiers.
Asked whether some of the recruits learning shooting and other skills would be part of the counter-offensive when they returned to Ukraine, the prime minister, speaking in English, said: "On this training base, our future soldiers – guys and girls – are… having all special knowledge and experiences, practical experiences, for the battlefield."
As for why it was taking so long for the Ukrainian military officially to begin its offensive, Mr Shmyhal said: "We are preparing very carefully because it's a very important operation and we understand that we should demonstrate success in this operation to our society, to our partners, to all the world [and] to our enemy."
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During the visit last Friday, he said troops were readying themselves for the operation, with training, weapons and ammunition. Also, Ukraine was working closely with its partners.
"We will begin…when [it] is proper time, when it will be absolutely ready… we will begin counter-offensive immediately when our military and political leadership will make the decision."
The prime minister reiterated denials by his president that Ukraine had anything to do with a drone attack against the Kremlin in Moscow last week that Russian officials have claimed was intended to kill Mr Putin.
Mr Shmyhal said, instead, it seemed likely to have been some kind of "false flag" operation.
"We think that mostly false flag, but we have no more data," he said. "It's not a Ukrainian operation."