There are already foreign troops there in various capacities. The US allows active military members to 'resign', go to Ukraine and 'serve', return to the US and re-enter the military. There are 'work-arounds'. One in particular was a female military medic who left the mil, went to Ukraine and was interviewed while stocking an ambulance with med supplies, and later reported killed.
“””””The US allows active military members to ‘resign’, go to Ukraine and ‘serve’, return to the US and re-enter the military.”””””
No they aren’t. Tell us more about that female medic, perhaps her name.