After three years spent trying to deter Russia from destroying Ukraine, European Union leaders grappled on Monday with how to respond to a major ally who appears determined to start a trade war or even seize part of their territory.

Prime Minister Keir Starmer had hoped to spend Monday marking a new milestone in the UK’s much-promised reset with European Union five years after Brexit. Instead, he received a dramatic reminder of how much harder that will be with Donald Trump back in the White House.

Donald Trump is considering plans to impose a 10 per cent tariff on the EU, The Telegraph understands. The move would pour fuel on a blooming global trade war, which began at the weekend when the US president slapped sweeping levies on goods imported from Mexico, Canada and China.