Labuan would be secured to control the entrance to Brunei Bay, and would be developed as an airbase. In the planning phase of the operation, the Allied high commands differed in their opinions about the necessity of securing Brunei, with the British Chiefs of Staff Committee believing it would take too long to develop the area for it to be developed for it to be used in operations. They were also concerned that it would divert the British Pacific Fleet from the main theatre of operations off Japan and instead favoured establishing a fleet base in the Philippines. The United States Joint Chiefs of Staff, however, approved the operation believing that it could support future operations in south-east Asia. In preparation for the landings, commencing in March, the Allied Services Reconnaissance Department (also known as Special Operations Australia) began Operation Agas in North Borneo, and Operation Semut in Sarawak; these were clandestine operations to gather information and organise local Dayak tribesmen to carry out guerrilla operations following the main landings. Ultimately, five Allied parties would be inserted into Borneo as part of Operation Agas, while four were deployed under Semut. Preliminary aerial bombardment of northern Borneo by Australian and US aircraft began on 3 May, before being concentrated on the main landing areas on 5 June. Meanwhile, minesweepers began to clear sea lines of communication for the large Allied naval task force that was assigned to support the operation. This force was designated as Task Force 78.1 and consisted of Australian and US warships, under the command of Rear Admiral Forrest B. Royal. Initially, the Allies planned to launch operations in North Borneo in late May, but shipping shortages delayed moving the assault troops to their staging base on Morotai Island and resulted in the operation being delayed until early June. Opposing forces A total of 29,000–30,000 men were committed by the Allies to secure North Borneo, with the majority of the ground forces being provided by the Australian 9th Division, under the command of Major General George Wootten. The 9th Division consisted of three brigades—the 20th, 24th and 26th Brigades—however, at the time of the North Borneo operations, the 26th was engaged at Tarakan having been detached from the division in May 1945, so only two brigades were allocated to operations in North Borneo. Part of the all-volunteer Second Australian Imperial Force, the 9th Division was a veteran formation,