US halts antitrust cooperation with Canada amid trade dispute

The US Justice Department has ordered its antitrust division to stop cooperating with Canada, according to a Wall Street Journal report based on internal emails, adding a new pressure point to the trade dispute between Washington and Ottawa.

Lynda Marshall, chief of the division’s international section, told officials in an email on Wednesday to halt cooperation on cases and policy engagement with Canadian authorities. The message did not give a reason for the directive. Section chiefs were later asked to submit lists of their areas of cooperation with Canada by the end of Friday.

The reported action would mark another escalation in a dispute between two neighboring countries that have been close allies for decades. Their relationship has deteriorated over trade and other issues since Donald Trump returned to the White House in early 2025. The dispute has produced tariffs covering tens of billions of dollars in cross-border trade.

Trump has repeatedly suggested that Canada should become a US state. Last week, he ordered Lake Ontario to be renamed “Lake America” for US federal government purposes, a change that does not affect what Canada or others call the lake.

The White House, the Justice Department and the Canadian government did not immediately respond to requests for comment.

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Lake America