More than 20 nations supporting Ukraine have pledged to take Russian oil and gas off the global market as part of efforts to pressure President Vladimir Putin to end the war.
We're choking off funding for Russia's war machine, said UK Prime Minister Sir Keir Starmer, after hosting a summit of the so-called coalition of the willing in London.
The UK and US have in recent days sanctioned Russia's two biggest oil companies, while the EU targeted Moscow's liquefied natural gas (LNG) exports.
Ukrainian President Volodymyr Zelensky, who was also in London, said pressure on Russia was the only way to stop the fighting. However, no long-range missile deliveries were announced at the summit.
Zelensky has long argued that US-made Tomahawks and European missiles would help make the war costs heavier for Moscow by hitting key military targets – including oil refineries and weapons depots – deep inside Russia.
But during last week's talks in Washington, US President Donald Trump indicated to Zelensky that he was not ready to supply Tomahawks.
On Thursday, Putin warned that if such weapons are used to strike Russian Federation territory the response will be... overwhelming.
Russia launched its full-scale invasion in February 2022 and currently controls around a fifth of Ukrainian territory, including the Crimean peninsula that it annexed in 2014.
Speaking at a joint press conference after the London summit, Sir Keir said Putin was not serious about peace, and therefore Ukraine's allies agreed a clear plan for the rest of the year on supporting Ukraine.
The UK prime minister said this also included targeting Russia's sovereign assets to unlock billions to help finance Ukraine's defence. He gave no further details.
On Thursday, EU leaders agreed to help support Ukraine's financial needs for the next two years, but stopped short of agreeing to use frozen Russian assets worth €140bn (£122bn).
Asked about a so-called reparations loan for Ukraine funded by the Russian assets, Danish Prime Minister Mette Frederiksen said she hoped a decision would be made by Christmas Eve.
In London, the coalition of the willing also pledged to strengthen Ukraine's air defences amid almost daily Russian air assaults on Ukrainian civilians and energy infrastructure.
Zelensky warned that Russia wants to make the winter cold a tool of torment, adding: They want to break us.
Comments by the leaders in London will be disappointing for those who were hoping to hear specific examples of how Kyiv's allies were planning to prevent Russia from attacking Ukraine.
Further support for Ukraine's energy infrastructure was among the issues discussed at the London summit - however, no specific announcements were made.
In Ukraine, several people who spoke to the BBC said they were more focused on everyday problems, rather than following Zelensky's trip to the UK.
Yana Kolomiets, from Odesa, said there was a lack of electricity, heating and water in the southern city.
The more scary thing is that the Russians started launching guided bombs on our region, she added.
Tetiana Dankevych, from the capital Kyiv, said power outages and a problems with water supplies caused by Russian strikes were making life very difficult.
I don't have a feeling this war will end soon, she said.
Dutch Prime Minister Dick Schoof and Nato Secretary General Mark Rutte also took part in the London meeting, while other leaders - including French President Emmanuel Macron - participated via a video link.
