Trump argued over the weekend that other world leaders indicated they would support letting Russia back into the group. But Donald Tusk, the head of the European Council, said Saturday that "under no condition" could G-7 nations allow Russia to return.

“One year ago, in Canada, President Trump suggested reinviting Russia to G7, stating openly that Crimea’s annexation by Russia was partially justified. And that we should accept this fact,” Tusk said, according to Reuters.

Trump's comments on Russia were one of several controversies that emerged from the global strategy session. Trump also skipped a climate meeting, floated his Miami golf course as a possible location for next year's meeting and lashed out at the media throughout the summit.

"This weekend’s G-7 summit was another missed opportunity for President Trump to show America’s strength by unifying key global partners to address the numerous challenges facing our planet," Schumer added on Monday.