The Secretary of Defense shall make such changes to Department of Defense Instruction 5111.20 (relating to the State Partnership Program) (or a successor instruction) as may be necessary to ensure that, in performing selection analysis for the State Partnership Program under section 341 of title 10, United States Code, the Chief of the National Guard Bureau— (1) considers the number of current partnerships assigned to the National Guard of a State; and (2) gives preference to States that have only one active assigned country under the program.