President Donald Trump has given his backing to NATO but has told European nations they must spend more on defence - and he is not wrong. The United States gives the necessary muscle to NATO but it comes at a big cost and quite rightly the US government is calling for other nations to pay their share as well. If the US grows cold towards NATO, then it will be a question of thank you and goodnight for the alliance formed at the height of the Cold War. Europe may make big statements about a European army and a common European defence policy, which may look rather nice on paper but in practice it is little more than a Home Guard. And Europe is facing some serious threats both from Russia and Islamic State terrorists.