Uncertainty is the word of the day in the US as Donald Trump gears up for his so called "Liberation Day".  

The President will reveal his latest round of tariffs at 9am New Zealand time.  

It's expected to throw away decades of norms around global trade and hit people in their back pockets.  

University of Iowa Economics Professor Anne Villamil told Andrew Dickens there's particular concern around further tariffs on Canada.  

She says 80% of US aluminium imports come from Canada, which is a key manufacturing component.  

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