Mont. Code Ann. § 26-1-1103

This part applies to an unsworn declaration by a declarant who at the time of making the declaration is physically located outside the boundaries of the United States whether or not the location is subject to the jurisdiction of the United States. This part does not apply to a declaration by a declarant who is physically located on property that is within the boundaries of the United States and subject to the jurisdiction of another country or a federally recognized Indian tribe.