Border States Security Improvement Act - Authorizes the Secretary of Defense to provide funds to the governor of a state to employ units or members of that state's National Guard, state defense forces, and law enforcement agencies to help secure an international border that forms part of that state's border.
Directs the Secretary to: (1) provide the requested funds for such use of the National Guard even though the border security activities are conducted while National Guard members are not in federal service; and (2) pay a state an amount that the governor certifies is necessary for expenses of such activities from funds available to the Department of Defense (DOD) for homeland defense.