Trump has also threatened to introduce tariffs - a tax on imports - on goods from Canada and Mexico, but paused these for 30 days after both countries agreed to boost border security. The US president has said tariffs are needed to help the American economy and to "protect" the country from the "major threat of illegal aliens and deadly drugs".

U.S. President Donald Trump has said that although Britain was "out of line" when it came to trade he thought it may be able to avoid tariffs, adding of the imbalance: "I think that one can be worked out.