With the well-telegraphed arrival of Canadian retaliatory tariffs on US products on Tuesday, importers, exporters and trade officials waited to see which side would blink first with billions of dollars at risk in one of the world’s largest trading relationships.At midnight, Canadian tariffs of up to 50 per cent took effect on C$27.6 billion (US$19.9 billion) worth of steel, aluminium, apparel, farm equipment and other American goods, escalating an economic stand-off that saw negotiations break down and US President Donald Trump announce sweeping duties on Canadian products.Hours before Canada’s tariffs took effect, Trump opened a new front by threatening to block sales of Bombardier aircraft in the US unless the Quebec-based plane maker moved its manufacturing there.By Tuesday afternoon, Trump had extended his list of grievances to the dairy industry and government procurement.“Canada has been ripping us off for years,” he wrote in a lengthy social media post. “That is not reciprocity, it is a Canadian Trade Scam.”Bombardier responded by highlighting the tens of thousands of US jobs it supports through its operations and supply chain.