text: is it possible to join another countrys military? me and a friend were talking about the military and he said he wanted to go to italy and join the italian military. i'm not sure if this is possible since he is an american born citizen. any help? i believe you can join certain divisions of the italian military if you are a non-citizen. doing so will:  1)automatically grant you italian citizenship. 2)will not invalidate your american citizenship (as long as the country whose military you are joining is not at war against the us).  for example, a number of naturalized us citizens of jewish decent go back to israel become dual citizens and serve within the israeli defense forces without penalty to their us citizenship.  a us supreme court ruling in the 1960s stated that the only way an american can lose his or her citizenship is if he or she formally renounces it.