Democratic leaders and Sen. John McCain on Saturday night criticized President Trump for his comments about the G7 summit about trade and Russia. Mr. Trump had signed the official G7 communique before leaving, but hours later, he tweeted that he had instructed his representatives "not to endorse" the final statement.

McCain tweeted "To our allies: bipartisan majorities of Americans remain pro-free trade, pro-globalization & supportive of alliances based on 70 years of shared values. Americans stand with you, even if our president doesn't."

To our allies: bipartisan majorities of Americans remain pro-free trade, pro-globalization & supportive of alliances based on 70 years of shared values. Americans stand with you, even if our president doesn’t. — John McCain (@SenJohnMcCain) June 10, 2018

Mr. Trump's tweets followed a press conference by Canadian Prime Minister Justin Trudeau, who said that Canada would be going through with retaliatory tariffs given the U.S.'s insistence on steel and aluminum imports.

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"Canadians, we're polite, we're reasonable, but we also will not be pushed around," Trudeau said.

Mr. Trump then tweeted that "based on Justin's false statements, and the fact that Canada is charging massive Tariffs to our U.S. farmers," he would not be following the final communique.

House Minority Leader Nancy Pelosi, D-California, tweeted Mr. Trump had "alienated our allies."

This week started with @realDonaldTrump boosting a Chinese company identified as a national security threat to the U.S. It ended with him standing up for Russia and alienating our allies at the G7. #MAGA — Nancy Pelosi (@NancyPelosi) June 9, 2018

Pelosi also referenced Mr. Trump's earlier comments that the G7 should allow Russia back in. Russia was expelled from what was then called the G8 after the country's annexation of Crimea in 2014.

Senate Minority Leader Chuck Schumer, D-New York, tweeted that "it's hard to tell" if the U.S. is acting in the best interest of its national security, or Russia's.

Are we executing Putin’s diplomatic and national security strategy or AMERICA’s diplomatic and national security strategy? After the last few days, it’s hard to tell. — Chuck Schumer (@SenSchumer) June 9, 2018

Mr. Trump, who arrived at the summit late, left early Saturday, departing for Singapore for his summit with North Korean leader Kim Jong Un. Mr. Trump declared tariffs were the most important topic at the G7 summit, blasting ally nations for what he sees as them taking advantage of the U.S. He said other nations have been treating the U.S. like the "piggy back that everybody's robbing."