Conservatives are bashing Donald Trump for launching the 'dumbest trade war in history' with Canada as a risky gambit that could tank the US economy.

Trump's 50% Canada tariffs could raise costs, push up prices and hurt US businesses as retaliation risks grow, adding pressure to the US economy.

In a critical exchange, the United States cautioned Canada against pursuing a trade war, labeling it as a reckless move that could lead to severe repercussions. Following a…