Donald Trump has threatened to pull the US out of the global postal system, after receiving a letter from the inventor of the "Mighty Mug".

Jayme Smaldone tells Manuela Saragosa how he was prompted to write the letter by the inexplicably low prices that Chinese knock-offs of his product were able to charge on online retail platforms in the US.

It all boiled down to the arcane system of international postal charges set by the Universal Postal Union way back in the 1800s, as Washington DC-based lawyer Jim Campbell explains. And according to Gary Huang of the American Chamber of Commerce in Shanghai, some Chinese businesses are profiting enormously.

(Picture: Mighty Mugs; Credit: Mighty Mug)