Morotai was an island in the Halmahera group of the Dutch East Indies (present-day Indonesia) that was a key staging point and airbase for American operations in the Phillipines and Australian operations in Borneo. US troops originally landed on the island on 15 September 1944 and secured a perimeter around the island's airfield. Although that perimeter was subsequently enlarged, Japanese forces on the rest of the island were essentially left alone for the rest of the war.