Mont. Code Ann. § 77-6-103

The board, when it considers it in the public interest, may lease to the United States for military purposes any state land, whether such land was received by the state through federal land grants or whether such land consists of so-called "mortgage lands", on such terms and conditions as it considers necessary to promote the public welfare and protect the interests of the state. Rental shall be payable at the end of each year of the lease.