WASHINGTON (Kyodo) -- U.S. President Donald Trump said Thursday he wants to see a revival of the Group of Eight framework comprising Russia and major democracies including Germany, Japan and the United States.

Trump said if the G8 still existed there would not have been a war in Ukraine. "I think it would have been very helpful, and it still would be helpful to have Russia be a part of that mix," he told reporters in the Oval Office.

Trump said during his first presidency he advocated the idea of allowing Russia to rejoin the Group of Seven and the late Japanese Prime Minister Shinzo Abe "agreed with me 100 percent and some of the others did too."

Trump also said Ukraine and others will be part of the forthcoming negotiations between the United States and Russia to end the war.

Trump's remarks came a day after he held separate phone calls with Russian President Vladimir Putin and Ukrainian President Volodymyr Zelenskyy.

Trump agreed with them to begin talks as soon as possible toward stopping Russia's full-scale invasion of Ukraine that started nearly three years ago.

The G8 was created in 1997, with Russia formally becoming the eighth member to regularly discuss global issues with the G7 countries, also including Britain, Canada, France and Italy. But Russia was removed from the framework after it occupied and annexed the autonomous Ukrainian region of Crimea.

On Thursday, Trump also said he and Putin have agreed to advance denuclearization efforts "in a very big way."

"There's no reason for us to be building brand new nuclear weapons. We already have so many. You could destroy the world 50 times over, 100 times over," he said, adding, "China's trying to catch up."

He expressed his intention to engage with both Putin and Chinese President Xi Jinping, starting off separately and later all together, to reduce nuclear weapons.

When asked by a reporter if he would travel to China for a meeting, Trump said, "It never bothered me. I'm willing to say I'll go first. It doesn't matter. It's the end result that counts."