His expertise in airbase construction led to Johns being sent to the South West Pacific as Chief Engineer, American Forces in Java. Departing Washington, D.C. by air on 14 January 1942, Johns arrived in Surabaya nine days later. His first mission was to provide airfield facilities on Java for 2,000 aircraft. Tapping into the vast resources of labour available in one of the world's most densely populated regions, Johns set about readying the required airfields. However, Java was captured by the Japanese before the aircraft arrived.