U.S. President Donald Trump threatened to impose 200 percent tariffs on French wine and Champagne late Monday in response to Emmanuel Macron rejecting his offer to join the “Board of Peace” tasked with overseeing the next steps in Gaza.

Informed by a reporter that the French president had said he wouldn’t join the board because of concerns about its powers, Trump dismissed Macron as lacking influence and said he would be “out of office in a few months.”

“I’ll put a 200 percent tariff on his wines and Champagnes, and he’ll join, but he doesn’t have to join,” Trump said during a huddle with the media.

In response, a French official close to Macron who was granted anonymity as they are not authorized to speak on the record, told POLITICO: “We have taken note of Mr. Trump’s statements on wines and Champagnes. As we have always emphasized, tariff threats to influence our foreign policy are unacceptable and ineffective.”

Trump announced the establishment of the board — which he touted as “the Greatest and Most Prestigious Board ever assembled at any time, any place” — on Friday as a key part of his 20-point plan to end the war between Israel and Hamas. An assortment of world leaders have been invited to join, including Russian President Vladimir Putin and Belarusian leader Alexander Lukashenko.

Bloomberg reported Tuesday that Trump wants the board’s full constitution and remit to be nailed down at the World Economic Forum in Davos on Thursday — but some countries are uneasy about the details of the proposal.

France’s decision to reject the offer was taken over concerns that the board, chaired by Trump, would have extensive powers beyond transitional governance of the Gaza Strip and undermine the United Nations framework.

A statement from Macron’s office noted that the board’s charter “goes beyond the framework of Gaza and raises serious questions, in particular with respect to the principles and structure of the United Nations, which cannot be called into question.”

Clea Caulcutt and Benjamin Johansen contributed to this report.