These achievements were honoured by the prefix "Royal", conferred by King George VI in 1947. Twenty of the pre-war squadrons were reformed postwar as fighter units. Events after the Second World War heralded a time of great danger for the UK. The onset of the Cold War with the Communist Bloc leading to the Berlin Air Lift and ultimately the outbreak of the Korean War in June 1950. During these crises the RAuxAF fighter squadrons, the five newly formed Air Observation Post (AOP) squadrons and other RAuxAF units, played their part in the UK's air defence and participated in many NATO air exercises. In 1951, at the height of the Korean War, all 20 RAuxAF fighter squadrons (representing one third of Fighter Command strength) were called up for three months full-time service; they were required for home defence in place of regular squadrons earmarked for deployment to Korea. In the event RAF fighter squadrons were not needed in Korea, but the RAuxAF squadrons were retained for intensive refresher training at their home bases.