Makes sense, things got really butchered in the translation. Our police used to be green until, what feels like really recently. So there are still a lot of sayings around involving "the people in green". Now they are apparently blue across the EU.
To me, "little green men" meant aliens.
“Little green men” to me is a reference to the Russian army units that invaded Ukraine without insignia for deniability.
Thats a rather recent one however. The saying is rather old.
Usually, but in this context it's clear that it isn't.