President Donald Trump’s participation in Wednesday’s annual NATO summit meeting has turned a once routine reaffirmation into a high stakes gamble on the United States’ continued commitment to the alliance.

In the week leading up to the meeting, Trump has already warned fellow NATO members to increase their expenditures toward joint military defense. At a campaign rally last week in Great Falls, Montana, the president told supporters, “I’ll see NATO and I’ll tell NATO, ‘You’ve got to start paying your bills.’” He then warned alliance members, “The United States is not going to take care of everything.”

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The U.S. currently funds 72 percent of NATO’s total defense spending. Trump has previously criticized European leaders for failing to fulfill their 2014 goal of spending two percent of their gross domestic product on defense for the alliance. While the 2014 pledge commits allies to “move toward” two percent, Trump disagrees claiming that two percent is the “bare minimum.”

With talks with Russian President Vladimir Putin set to commence only days after the summit, critics are wary about Trump’s commitment to NATO, which has previously cited Russia as a primary threat to European collective security. Just last month, Trump insisted that Russia should be readmitted into the G-7 Summit, after it was previously suspended for invading the Ukraine and annexing Crimea. 

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When comparing his anticipated meetings with NATO and Putin, Trump told reporters, “Putin may be the easiest of them all.”

Others also worry that Trump has irresponsibly conflated economic gain with national security. Amidst a trade war with fellow alliance members, including the E.U. and Canada, following Trump’s enactment of several trade tarriffs, the president’s “America First” policy could prove disastrous for the alliance. In a recent tweet concerning the upcoming summit, Trump also referenced the U.S.’s trade imbalance with the E.U.

Daniel Price, a former international economic adviser to President George W. Bush and White House veteran to major summit meetings, has denounced the president’s business-like mindset, attributing to it a loss of confidence amongst allies, “In the past, Europe did not doubt that U.S. interests and values were fundamentally aligned with theirs,” said Price. “Now they wonder whether they can count on us in times of crisis without our first checking to see if they are current on their rent or royalty payments.”