Airfields were constructed by prisoners of war and conscripted labour from various locations, including from Brunei, Labuan, Ranau and Elopura. Before the Japanese occupation, there were only three airfields: in Kuching; Miri; and Bintulu in Sarawak, while in North Borneo there were none. Due to this, the Japanese planned to construct a total of twelve airfields in different parts of northern Borneo to strengthen its defence, of which seven were to be located in Api, Elopura, Keningau, Kudat, Tawau, Labuan and Lahad Datu. The Japanese also launched a series of road projects in North Borneo, with the roads linking Ranau with Keningau and Kota Belud with Tenghilan to be improved as well a new road linking Kudat and Kota Belud to be constructed. As these roads passed through mountainous areas, a large number of forced labourers were needed to realise the projects. In preparing for Allied retaliation Lieutenant general Masataka Yamawaki created an indigenous force consisting of around 1,300 men in 1944. Most of them were stationed in Kuching, with others in Miri, Api and Elopura; all were tasked to maintain peace and order, gather intelligence and to recruit. Brunei harbour was also used by the IJN as a refuelling depot and as a staging post for the Battle of Leyte Gulf.