President Donald Trump is threatening to block the opening of a new bridge connecting the United States and Canada.

The Gordie Howe International Bridge is expected to open later this year after a period of testing, according to CNN. The 1.5-mile span will connect Detroit and Windsor, Ontario.

But Trump said in a Truth Social post that he would “not allow” the bridge to open.

“I will not allow this bridge to open until the United States is fully compensated for everything we have given them, and also, importantly, Canada treats the United States with the Fairness and Respect that we deserve. We will start negotiations, IMMEDIATELY.”

It was not clear how Trump would block the bridge from opening. It is operated by the Windsor-Detroit Bridge Authority, according to CNN.

Canada has paid for the entire cost of the $5.7 billion project, according to the Detroit Free Press.

Trump said Canada has treated the U.S. badly for decades, according to the Free Press. He noted many Canadian provinces are not even stocking U.S. liquor since he began imposing tariffs on Canadian imports during his first term.

He also said the bridge was built with no U.S. content for products like steel.

“With all that we have given them, we should own, perhaps, at least one half of this asset,” Trump wrote.

The bridge is already owned jointly by the U.S. and Canada, according to the Free Press.

Trump’s threat to block the bridge opening is part of his larger pressure campaign to get Canada to give in to his demands, according to The New York Times.

He has threatened to annex Canada and make it the 51st state in addition to waging a trade war using tariffs. He has also threatened other economic sanctions.

The bridge project broke ground in 2018.

The Canadian Chamber of Commerce, the nation’s largest business lobbying group, denounced Trump’s threat in a statement, writing that “whether this proves real or simply threatened to keep uncertainty high — blocking or barricading bridges is a self-defeating move.”