Tariffs of 15, 25 or 50 per cent on steel, cheese and agricultural equipment, among other things - that is Canada's response, which now comes into effect after trade talks with the US broke down.
The former good neighbours have been trading verbal blows for weeks over the two countries' economies as well as their leaders.
The heart of the dispute concerns who should be the main industrial engine, mainly in the automotive sector, but Donald Trump has recently also targeted Canadian aircraft manufacturer Bombardier.
Canada's Mark Carney will speak next week in the European Parliament.
The world is waiting to see what happens next, says Daniel Béland, a political scientist at McGill University in Montreal.
