Macron isn't saying that europe needs an army to protect itself against the USA militarily, he's saying europe needs an army because under Trump, european security is unpredictable. Trump tears up international treaties. Europe already knows how, under Obama, the USA is directing its defence strategy away from europe and towards the pacific. Trump just adds to the uncertainty. The EU Army is a concept which has its origins in the European Security and Defence Policy of the European Union of 1999 and the formation of the Common Security and Defence Policy (CSDP) of 2009, the Lisbon Treaty. Macron is simply saying that the EU needs to move things along. It's hardly pie in the sky thinking. Trident Juncture is a current exercise in Norway involving 51,000 men, 10,000 tanks, 250 planes and 65 vessels. It includes all the nato countries plus Sweden and Finland. If nato cannot rely on the USA, europe will have to make up the numbers that the USA currently provides.