believed that holding the Solomon Islands would be ultimately unsuccessful and that it would be better to wait for an Allied attack on Bougainville which would be much less costly to supply and reinforce. The Imperial Japanese Navy (IJN) preferred to delay the Allied advance for as long as possible by maintaining a distant line of defense. With no effective central command, the two Japanese services implemented their own plans: the navy assumed responsibility for the defense of the central Solomons and the army for the northern Solomons. In early 1943, Japanese defenses were prepared against possible Allied landings on New Georgia, Kolombangara and Santa Isabel. By June 1943, there were 10,500 troops on New Georgia and 9,000 on Kolombangara, all under the command of General Minoru (Noboru) Sasaki, well dug in and waiting for an Allied attack. Allied planning Choice of New Georgia By early 1943, some Allied leaders had wanted to focus on capturing Rabaul, but Japanese strength there and lack of landing craft meant that such an operation was not practical in 1943. Instead, on the initiative of the U.S. Joint Chiefs of Staff and the South West Pacific Area's staff, including General Douglas MacArthur, a plan known as Operation Cartwheel was developed, which proposed to envelop and cut off Rabaul without capturing it, by simultaneous offensives in the Territory of New Guinea and northward through the Solomon Islands. The Allied base at Guadalcanal continued to suffer from Japanese bombing raids even after the island was declared secured on 9 February 1943. The Japanese airfield at Munda made these raids easier by giving Japanese planes a convenient place to refuel on the way to and from their main base at Rabaul. The Allies attempted to neutralize Munda with repeated bombing raids and naval shelling, but the Japanese were always able to repair the airfield in short order. The Allied command thus determined that Munda had to be captured by ground troops. Since the New Georgias lay within the South West Pacific Area, which was any area of the Solomon Islands west of longitude 159° east, the operation would be the responsibility of MacArthur and would be conducted by Admiral William F. Halsey's forces. Halsey's operations east of longitude 159° east reported to Admiral Chester Nimitz. Commander South Pacific Force (renamed US Third Fleet on 15 March 1943), headquartered at Nouméa on New Caledonia. US forces committed to