Trump had announced – then halted – 25% levies on Canadian and Mexican imports this month over illegal immigration and deadly fentanyl, with Canadian energy to face a lower rate.

But the month-long pause ends March 4 and Trump wrote on social media Thursday that the proposed levies will happen as scheduled until the problem of fentanyl stops “or is seriously limited.”

“We are working day and night with one goal: to avoid the tariffs being imposed on Tuesday,” Trudeau told reporters in Montreal.

But if the measures come into force, “we will have an immediate and extremely strong response,” the outgoing Canadian premier said.

Trudeau has repeatedly stressed that less than 1% of the fentanyl and undocumented migrants that enter the US come through the Canadian border.

His government has however taken a series of steps aimed at addressing Trump’s concerns, including a C$1.3 billion plan to enhance border security.

Trudeau’s government has also named a fentanyl czar to coordinate efforts against the drug, and on Thursday the border services agency announced the launch of “Operation Blizzard,” an initiative to counter fentanyl trafficking.

Trudeau has said he will step down as prime minister when his Liberal Party chooses a new leader next month.