The US Armed Forces allow enlisting as a permanent resident: https://www.usa.gov/join-military https://www.usa.gov/join-military There are quite a few exceptio

The US Armed Forces allow enlisting as a permanent resident: https://www.usa.gov/join-military https://www.usa.gov/join-military There are quite a few exceptions to "militaries don't recruit non-citizens": https://en.wikipedia.org/wiki/List_of_militaries_that_recruit_foreigners https://en.wikipedia.org/wiki/List_of_militaries_that_recrui... Most relevant to the case at hand, a number of EU countries allow EU citizens to serve in their militaries: Belgium, Denmark, Ireland and Luxembourg