Donald Tusk, the president of the European Union, released a letter to 27 EU leaders earlier this week indicating that the United States under President Trump is as much a threat to the future of Europe as Russia or China.

Donald Trump put EU leaders on their heels along the campaign trail when he pointed out how very few NATO member states actually fulfill their financial obligation to the alliance, and suggested that if they were unwilling to live up to their end of the bargain, the United States may not honor another portion of the NATO agreement stipulating that every nation come to the defense of an attacked member.

Leaders throughout Europe, suddenly faced with the possibility of having to defend their own borders with military forces that have atrophied due to neglect since NATO began relying heavily on the combined military might of the United States and other larger member nations, promptly set to work establishing a European defense fund—a move that could be seen as precursor to establishing a joint European army, which would effectively be NATO without American or British support.

EU President Donald Tusk’s letter laid out what he sees as the potential external risks the EU faces in the coming years. Among them: Russian aggression, Chinese assertiveness, radical Islam, and the United States of America.