The once tight-knit grouping has struggled to find unity as Washington retreats from multilateralism and Trump overtly expresses support for Russian President Vladimir Putin.
G7 leaders from Britain, Canada, France, Germany, Italy, Japan, and the U.S., along with the European Union, are convening in the resort area of Kananaskis in the Canadian Rockies until Tuesday.
Speaking alongside Canadian Prime Minister Mark Carney, Trump said the former Group of Eight had been wrong to kick out Russia in 2014 after it annexed Crimea.
"This was a big mistake," Trump said, adding he believed Russia would not have invaded Ukraine in 2022 had Putin not been ejected.
"Putin speaks to me. He doesn't speak to anybody else ... he's not a happy person about it. I can tell you that he basically doesn't even speak to the people that threw him out, and I agree with him," Trump said.
Though Trump stopped short of saying Russia should be reinstated in the group, his comments raise doubts about how much Ukrainian President Volodymyr Zelenskiy can achieve when he meets the leaders on Tuesday. European nations say they want to persuade Trump to back tougher sanctions on Moscow.
Zelenskiy said he planned to discuss new weapons purchases for Ukraine with Trump.
Trump spoke on Saturday with Putin and suggested the Russian leader could play a mediation role between Israel and Iran.
French President Emmanuel Macron dismissed the idea, arguing that Moscow could not be a negotiator because it had started an illegal
war against Ukraine.
A European diplomat said Trump's suggestion showed that Russia was very much on U.S. minds.
European officials said they hoped to use Tuesday's meeting with Zelenskiy and NATO Secretary General Mark Rutte and next week's NATO summit to convince Trump to toughen his stance.
"The G7 should have the objective for us to converge again, for Ukraine to get a ceasefire to lead to a robust and lasting peace, and in my view it's a question of seeing whether President Trump is ready to put forward much tougher sanctions on Russia," Macron said.
In another early sign the group of democracies may struggle to reach agreement on key issues, a U.S. official said Trump would not sign a draft statement calling for de-escalation of the Israel-Iran conflict.
A Canadian official, though, said the conflict would come up in bilateral meetings throughout the day and it was too early to speculate on the outcome of those conversations. A senior European diplomat echoed those comments, saying Trump had yet to make a decision.
DRAFT DOCUMENTS
Canada has abandoned any effort to adopt a comprehensive communique to avert a repeat of the 2018 summit in Quebec, when Trump instructed the U.S. delegation to withdraw its approval of the final communique after leaving.
Leaders have prepared several draft documents seen by Reuters, including on
migration, artificial intelligence, and
critical minerals. None of them have been approved by the United States, however, according to sources briefed on the documents.
Without Trump, it is unclear if there will be any declarations, a European diplomat said.
The first five months of Trump's second term upended foreign policy on Ukraine, raised anxiety over his closer ties to Russia, and resulted in
tariffs on U.S. allies.
Talks on Monday will centre around the economy, advancing trade deals, and China.
Several leaders arrived in Canada, a country Trump has repeatedly threatened to annex as the 51st U.S. state, in hopes of making progress on trade negotiations with the United States.
German Chancellor Friedrich Merz said he hoped there would be steps towards a solution to a tariff dispute with the United States, even if a solution itself could not be reached at the summit.
Britain and the United States should finalise "very soon" the implementation of a trade deal agreed last month, Prime Minister Keir Starmer said.
Britain was the first country to agree a deal for lower tariffs from Trump, but implementation has been delayed while details were finalised.
Source: Reuters