The Japanese occupied Bougainville in early 1942, building two air bases in the southern part of the island, one at the site of what would become Buin after the War and the other at Kahili.
"It was obvious to the planners that Japanese air power sited at Rabaul and at the Bougainville fields of Kahili, Buin, Kieta and Buka must be neutralized before the Empress Augusta Bay operation could take place."[REF] .