The Trump administration's top trade negotiator disputes Ottawa's assertion that last-minute demands from the U.S. derailed a trade deal between the two countries last week, saying Canadians' concerns about the deal's "implementation" led Ottawa to pull the plug.

The Canadians’ preparedness to walk away from talks with their US counterpart is the latest sign that Donald Trump’s bulldozer approach may be reaching its limits.

Canadian negotiators left Washington Friday without a deal to prevent President Donald Trump from enacting new 50% tariffs on about $20 billion worth of goods.