25 U.S.C. § 174

The President is authorized to exercise general superintendence and care over any tribe or nation which was removed upon an exchange of territory under authority of the act of May 28, 1830 , “to provide for an exchange of lands with the Indians residing in any of the States or Territories, and for their removal west of the Mississippi;” and to cause such tribe or nation to be protected, at their new residence, against all interruption or disturbance from any other tribe or nation of Indians, or from any other person or persons whatever.