Donald Trump has signed off on $60 billion-worth of tariffs on imports from China, deepening fears of a trade war and triggering a slide in US stocks. A short time ago, before signing a section 301 memorandum to unilaterally impose the tariffs, the president said addressing the United States' trade deficit was one of the main reasons he was elected. China has already indicated it will retaliate. A spokesperson has accused the US of abusing global trade rules. US correspondent Nick Harper joins us with his analysis.