The transatlantic response to the Ukraine conflict demonstrated the strength of the relationship between London and Washington, according to Rishi Sunak and Kamala Harris.
The Prime Minister met the US vice president for the first time on Saturday when they entered into talks on the fringes of the Munich security conference.
Ms Harris told Mr Sunak, before sitting down for their bilateral discussions, that the UK was “among our greatest of allies”.
Speaking in front of reporters, she said the pair would be touching upon “our transatlantic community, and how it has risen to meet the needs of supporting the Ukrainian people”.
The Prime Minister told Ms Harris he “completely agreed” with her sentiments about the importance of the UK-US relationship.
He added: “There could be no better illustration of that than our joint response to the awful conflict in Ukraine where we stood together and led, I think, the world in providing steadfast support to Ukraine so it can defend itself and push back against Russian aggression.”
The British leader said both their speeches at the German summit had stressed how that combined approach to aiding Kyiv “was the right strategy”.
Downing Street said the pair used their time together to discuss “how to accelerate international action on Ukraine, to allow them to win the war and secure a just and lasting peace”.
Mr Sunak and Ms Harris agreed on the “importance of thinking beyond Ukraine’s immediate needs” and starting to think about ensuring Kyiv “never faces the same threats again”.
A No 10 spokeswoman said: “They agreed that Putin’s war in Ukraine is a global war, both in terms of its impact on food and energy security and in terms of its implications for internationally accepted norms like sovereignty.
“The Prime Minister and Vice President Harris condemned those countries who have supported Putin’s efforts politically and militarily.”
The meeting with the vice president – who proved a big draw in the conference hall on Saturday afternoon – was one of many in the Bavarian capital for the Prime Minister.
He held talks with the leaders of the European Union, Germany, Poland, Sweden and Finland, while also meeting briefly with Nato secretary general Jens Stoltenberg.
The busy schedule was designed to press home the argument made in his summit speech, about providing immediate military assistance to Ukraine while also increasing its defence capabilities for the future.
Fresh off the plane from London Stansted, Mr Sunak went straight to meet German chancellor Olaf Scholz on Saturday morning.
Mr Sunak told the chancellor the West needed to think “about strengthening Ukraine’s long-term defences”.
Discussions then followed with Ursula von der Leyen, the European Commission president, with the two leaders touching upon both Kyiv’s struggle and issues with the Northern Ireland Protocol.
No 10 said the Brussels leader and the Prime Minister “agreed on the importance of giving Ukraine the military momentum they need to secure victory against tyranny”.
In the afternoon, the Conservative Party leader met Polish prime minister Mateusz Morawiecki, who had reportedly earlier told the summit how Warsaw wanted to discuss transferring its Soviet-era MiG fighter jets, as part of a wider coalition led by the US.
Mr Sunak, in comments made both to delegates and later to reporters, confirmed the UK would support any allies that were immediately ready to transfer fighter planes to the Ukrainian air force.
The Munich trip ended with a trilateral meeting with Swedish prime minister Ulf Kristersson and Finnish president Sauli Niinisto, leaders of two countries hoping to join Nato.
A Downing Street spokeswoman said: “The Prime Minister was clear that a Nato with Sweden and Finland in it will be stronger, and he expressed his hope that they would be able to join ahead of this summer’s Nato summit.”
Mr Sunak and his team arrived back to Stansted shortly after 7pm, making it a 12-hour roundtrip for the UK delegation.
