The Sentani area was occupied by Japanese forces in early 1942, following the invasion of the Dutch East Indies during the Pacific theater of World War II. Recognizing its strategic importance, the Japanese developed a major military base in the area. By 10 October 1943, a large airfield complex had been constructed, featuring two runways: a western runway measuring 4,500 ft and a southern runway measuring 6,200 ft. The facility included 24 large bomber revetments to the west of the strip and an additional 27 to the east, all connected by taxiways to the two runways. Air defenses initially consisted of four light anti-aircraft guns, which were later upgraded. Despite these defenses, the airfields were heavily cratered by American bombing raids. Originally built as a military airfield, construction was carried out rapidly and was primarily intended to accommodate Mitsubishi Zero fighter aircraft, which had a maximum takeoff weight of only 2.7 tons. As fighting with Allied forces intensified, the airfield was reinforced with hundreds of Japanese fighter aircraft. By April 1944, the Japanese had developed several airfields in the area: three had been completed, while a fourth was still under construction. Of these, only one was considered fully operational. These bases were captured by American forces during the Battle of Hollandia on 26 April 1944. During these engagements, the Allies reportedly lost only four aircraft. However, the runway itself was constructed with minimal preparation and was only roughly compacted, which made operations challenging. Fully loaded Allied bombers, in particular, faced difficulty taking off safely without risking collision with the nearby Cyclops Mountains. American engineers were then assigned to construct a new runway on the site of the former Japanese airfield. This new runway had to be stronger and capable of supporting American aircraft that were up to ten times heavier than the Japanese Zero fighters. The runway was reinforced and widened to accommodate long-range heavy bombers such as the B-29 Superfortress. Following their capture, the airfields were extensively reconstructed and transformed into a major command-and-control hub, supporting numerous operational units conducting combat missions with both fighter aircraft and heavy bombers. Under American control, the complex consisted of three principal military airfields: Hollandia, Sentani Airport, and Cyclops. By the end of the World War II, Hollandia Airfield had been abandoned and was gradually reclaimed by dense vegetation by the early 2010s. More recent aerial imagery indicates that a large-scale residential development is now underway on the site. Cyclops Airfield, a single-runway facility located to the northeast of Sentani and originally constructed by Japanese forces, was likewise abandoned and has since been absorbed into the expanding urban area of Sentani. The airfield is historically significant as it once served as the headquarters of Douglas MacArthur at Hollandia prior to the liberation of the Philippines. Sentani Airfield is the only part of the complex still in use as an airfield today. 308th Bombardment Wing (10 August-22 October 1944) 310th Bombardment Wing (6 May-18 September 1944) 85th Fighter Wing (24 July-24 October 1944) 3d Bombardment Group (12 May-16 November 1944) 312th Bombardment Group (June-19 November 1944) 49th Fighter Group (17 May-5 June 1944) 475th Fighter Group (15 May-14 July 1944) 317th Troop Carrier Group (June-17 November 1944) 418th Night Fighter Squadron (12 May-28 September 1944) After the World War II, the government of Netherlands New Guinea made use of the remaining infrastructure left behind by both Japanese and Allied forces. This included Sentani Airport, which served as the main airfield in the colonial capital during the Dutch administration. Subsequently, the Dutch established an aviation hub operated by KLM at Mokmer Airfield in Biak.