US President Donald Trump said on Thursday the United States would impose a 35% tariff on imports from Canada next month and planned to impose blanket tariffs of 15% or 20% on most other trading partners.

In a letter released on his social media platform, Trump told Canadian Prime Minister Mark Carney the new rate would go into effect on August 1 and would go up if Canada retaliated.

In a post on X late on Thursday, Carney said his government will continue to defend Canadian workers and businesses in their negotiations with the US as they work towards that deadline.

The 35% tariff is an increase from the current 25% rate that Trump had assigned to Canada and is a blow to Carney, who was seeking to agree a trade pact with Washington.

An exclusion for goods covered by the United States-Mexico-Canada Agreement (USMCA) on trade was expected to stay in place, and 10% tariffs on energy and fertilizer were also not set to change, though Trump had not made a final decision on those issues, an administration official said.

Trump complained in his letter about what he referred to as the flow of fentanyl from Canada as well as the country’s tariff- and non-tariff trade barriers that hurt US dairy farmers and others. He said the trade deficit was a threat to the US economy and national security.

“If Canada works with me to stop the flow of Fentanyl, we will, perhaps, consider an adjustment to this letter,” Trump wrote.

Canadian officials say a miniscule amount of fentanyl originates from Canada but they have taken measures to strengthen the border.

“Canada has made vital progress to stop the scourge of fentanyl in North America. We are committed to continuing to work with the United States to save lives and protect communities in both our countries,” Carney added in his X post late Tuesday.

The prime minister said last month that he and Trump had agreed to wrap up a new economic and security deal within 30 days.

Trump has broadened his trade war in recent days, setting new tariffs on a number of countries, including allies Japan and South Korea, along with a 50% tariff on copper.

In an interview with NBC News published on Thursday, Trump said other trading partners that had not yet received such letters would likely face blanket tariffs.

“Not everybody has to get a letter. You know that. We’re just setting our tariffs,” Trump said in the interview.

“We’re just going to say all of the remaining countries are going to pay, whether it’s 20% or 15%. We’ll work that out now,” Trump was quoted as saying by the network.

Canada is the second-largest US trading partner after Mexico, and the largest buyer of US exports. It bought $349.4 billion of US goods last year and exported $412.7 billion to the US, according to US Census Bureau data.

Carney, who led his Liberal Party to a comeback election victory earlier this year with a pledge to tackle trade challenges with the US, had been aiming to negotiate a trade deal with its key trading partner by July 21.

Trump, in his letter, did not specifically address how trade negotiations were proceeding, but he said the “tariffs may be modified, upward or downward, depending on our relationship with your Country.”

Last month, the Carney government scrapped a planned digital services tax targeting US technology firms after Trump abruptly called off trade talks saying the tax was a “blatant attack.”