The calls to enhance EU defence co-operation have become a constant refrain. Russian aggressiveness in Ukraine and the Baltics, the rise of mass migration and terrorism, conventional and cyber, and the threat by Donald Trump not to honour defence guarantees to Nato members, have all fed the drumbeat. Of EU states only Britain, Poland, Greece and Estonia currently meet the Nato spending target of at least 2 per cent of GDP on defence, while the US invests over twice EU member states’ total defence spend.[...]