Donald Trump's threat on Saturday to impose tariffs on eight European countries unless they support his plan to buy Greenland came as a shock. The US president said he would introduce a 10% levy on imports into the US on 1 February, rising to 25% from the summer if no deal is done. It is unclear whether these tariffs would be added to existing levies. France and Germany - part of the group of eight which includes the UK, Denmark, Norway, Sweden, the Netherlands and Finland - have said the European Union (EU) should be ready to act if Trump goes ahead with the taxes. But what options does Europe have to respond to the US? Beloud