Since they are separate, sovereign, nations, expect the US Supreme Court to uphold the Tribal actions should it ever get that far.   https://supreme.justia.com/cases/federal/us/436/49/

The U.S. ­Bureau of Indian Affairs will be under new management on January 20, 2017 and that might solve the problem without further action in the courts. 

 Santa Clara Pueblo v. Martinez, 436 U.S. 49 (1978)