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British Prime Minister Boris Johnson met the leaders of Denmark, Estonia, Finland, Iceland, Latvia, Lithuania, the Netherlands, Norway and Sweden as part of the Joint Expeditionary Force on Tuesday.
The leaders agreed that Russia must respect international humanitarian law and that they supported the investigations of the International Criminal Court into alleged war crimes.
"The world will hold Russia to account for its actions. [Russian President Vladimir] Putin must fail," they said.
"JEF nations remain committed to supporting Ukraine at pace with military aid to ensure Ukraine is best able to defend itself."
The leaders said Mr Putin’s actions were fundamentally challenging the security of the Euro-Atlantic area.
They said his actions were unacceptable and that no other nations should fall victim to attempts of violent expansionism.
Later on Tuesday, Mr Johnson held private talks with Swedish Prime Minister Magdalena Andersson and agreed that the “abhorrent assault” on Ukraine had “shifted European thinking”, Downing Street said.
“The pair agreed that their two nations should further strengthen their work together on disinformation and said they looked forward to British and Swedish forces exercising together as part of JEF in the coming months," a Downing Street spokeswoman said.
“Both agreed on the need to reduce dependency on Russian hydrocarbons and the prime minister said renewables were a key part of the UK’s energy security strategy.”
Mr Johnson and Ms Andersson agreed that the UK and Sweden “would continue to work closely to increase defence ties, combat climate change and ensure Putin fails”.
Finnish President Sauli Niinisto also met Mr Johnson and No 10 said the two leaders agreed that Mr Putin's “invasion had dramatically changed the landscape of European security”.
“The prime minister reiterated that sovereign countries should be able to choose their own future, without fear or threat from Russia,” the spokeswoman said.