The foreign secretary claimed Russia can be pushed out of the peninsula, which have claimed since 2014.
Oleksiy Reznikov warned World War Three was started when Russia attempted to invade Ukraine in February.
Aiden Aslin, 28, and Shaun Pinner, 48, have been held by Russian forces since April.
Sweden and Finland have been formally invited to join the alliance.
Defence secretary Ben Wallace said warned Putin does not lie when it comes to threats.
"this means conflict with the entire North Atlantic alliance; a World War Three. A complete catastrophe."
Andrey Gurulyov, a state Duma deputy, made the propaganda comments on Russian state TV.
Kyiv was hit with missiles for the first time in three weeks, killing one and injuring others.
"The UK is not led by Winston Churchill these days, but by a pathetic, shaggy-haired parody of him."
Yahoo News UK speaks to UK families who have taken in Ukrainian refugees to find out exactly what their experience of the Homes for Ukraine scheme has been.
The dedicated YouTube channel will dub pre-school favourites into Ukrainian for children settling in the UK.
The foreign secretary said support for Ukraine cannot waiver as she accused Russia of creating a global food crisis.
The foreign secretary has backtracked on comments she made saying the UK government would "support" Brits wanting to travel to fight in Ukraine.
Prominent Putin critic Alexi Navalny has been moved from the prison he was incarcerated in to an unknown location his team have said.
Although the new chain's restaurants across Russia still look very much like McDonald's, they are now under the name "Vkusno i Tochka", which translates as "Tasty and that's it".
The family of Aiden Aslin, 28, from Nottinghamshire - one of two British men sentenced to death in a Russian show trial - have called for him to be treated with respect.
"It's impossible — Do you understand? — impossible to build a fence around a country like Russia. And we do not intend to build that fence."
Aiden Aslin, 28, from Nottinghamshire, Shaun Pinner, 48, from Bedfordshire, were charged with being foreign mercenaries.
Rumours have been swirling over the state of the Russian president's health.
A former British intelligence officer has suggested the Russian president could be removed due to his health.
The latest claim was made by a Russian TV presenter known as 'Putin's voice' and relates to three British fighters facing the death penalty.
Aiden Aslin, originally from Nottinghamshire, joined the Ukrainian marines in 2018 and had been fighting with his unit in Mariupol during the Ukraine crisis.
'Perhaps it's time to acknowledge that Russia's special operation in Ukraine has come to an end, in a sense that a real war has started: World War Three.'
According to the Ukrainian Armed Forces, as of 31 May, 30,500 Russian soldiers have so far been killed.
Rumours about the Russian president's supposed blood cancer have been swirling for months.