Tracing roots to colonial militia formed in 1636, the National Guard provides the militia of US states, districts, commonwealths and territories. The Air National Guard was split away from the Army National Guard in 1947, concurrent with the creation of the USAF. Guard units also act as a federal reserve; when 'federalized' by order of the President, ANG units form part of the active USAF. Traditionally equipped with much older hand-me-down aircraft types than regular USAF units, the introduction of the Total Force concept in the aftermath of the Vietnam War saw the ANG re-equipped with more modern types, receiving some new-build aircraft for the first time and more aircraft assigned to squadrons. President Reagan's military build-up of the 1980s accelerated ANG reform while the ANG took on an increasing responsibility for national air defence. Take a step inside the day-to-day operations of the ANG in the 1980s.