Military Installation Resilience Assuredness Act This bill requires commanders of major military installations to address installation resilience in master plans. A master plan shall address the following: risks and threats, which include disaster-related and environmental conditions; assets or infrastructure located on the military installation vulnerable to the risks and threats; lessons learned from the impacts of extreme weather events; measures to mitigate the impacts of risks and threats; community infrastructure and resources located outside the installation; agreements with other entities to maintain or enhance military installation or community infrastructure resilience; and projections from recognized governmental and scientific entities regarding future risks and threats to the resilience of a project considered in the plan during a 50-year installation lifespan. The bill includes, as major installations, medium sites (as defined in the most recent version of the Department of Defense Base Structure Report issued before the time interval prescribed for development of master plans arises).