Joining a Military not of your citizenship?

Hi, I was adopted from mongolia as a child to american citizens. I later found out and always questioned that i wasn't mongolian. I found out I'm of Turkmenistan descent. I have no way to prove it but found out I am. I want to join its military but I'm a American citizen. I have no way of proving I'm a Turkmen. Am i able to join there military. Does anybody have links?I'm 23 years old by the way. If I have to give up my citizenship I will. I feel this is something I have to do. Any help going about it?