In order to create a suitable defense system at its perimeter, the Japanese navy decided to develop some of the atolls of the Marshall Islands into bases for seaplane, naval surface units submarines, and, with the advent of long-range land-based bombers, as airfields. Taroa was to become a major airbase. The development of Taroa base began in December 1939, when a battalion of Japanese prisoners was drafted for the construction of the airfield.
The Japanese constructed an airfield with two runways (4800′ + 4100′), two hangars and a service apron. At the beginning of the US bombing a third runway had been begun. By end of 1943 there was a total of 380 buildings on Taroa (with >=490,000 square feet floor space), 80 of which had a floor space greater than 50 feet square. It had several power stations, a command centre, an air operations centre, fuel farms (35,000 gals.), a pier for larger ships, several ammunition bunkers, a large barracks area, and an extensive workshop area. The garrison had an extensive road network serviced by over 70 vehicles.