These days, it appears that anyone with reliable internet access can tap into commercial radar satellites to do their own version of airbase monitoring.
Back in 1955, the Soviet Union flew its bombers in a loop over an air show to give the illusion of having more aircraft than were actually in its arsenal, a move that caused alarm in the West. The resulting ‘bomber gap’ was finally disproven when U2 aircraft were able to systematically photograph Russian airbases. […]