President Trump announced today that he would give the U.S.’s biggest trading partner, Mexico, another 90 days to negotiate to a trade deal. The move came just hours before the White House was set to impose heavier tariffs on Mexico’s exports.

Dozens of other countries did not receive a similar reprieve. So, just after midnight tonight, steep U.S. tariffs on goods from those countries are set to snap into effect. That includes products from Canada, America’s second-largest trading partner, which is set to face a 35 percent tariff beginning tomorrow. Trump said it would be would be “very hard” to reach a trade deal with Canada after its prime minister said yesterday that he planned to back Palestinian statehood.

Several other countries, including Britain, Indonesia, the Philippines, Japan and the E.U., have reached preliminary deals with Trump. They have agreed for their exports to be subject to U.S. tariffs of 10 to 20 percent — lower than what the president had threatened, but still vastly higher than historical levels.

But although the administration has disclosed some tariff rates for countries on the president’s social media account or in fact sheets, the specific rates that importers and exporters will need to pay to move certain goods across U.S. borders remain unclear.

For more: Several countries have secured trade deals by offering flashy pledges of investment in the U.S. The details remain murky.