Why the US removed the exemption

From the BBC World Service: There's one word that's dominated the headlines this year: tariffs. Countries around the world have been grappling with the U.S. import taxes central to President Donald Trump's trade policy, so how are countries faring? We check in on Mexico, China, and others. Plus, the Trump administration eliminated the tax exemption for parcels under $800 this year. We investigate how the move is playing out four months on.