According to the planners, Formosa would have provided a suitable base for the strategic bombing campaign against Japan as well as a staging area for the foreseen invasion of the Japanese home islands.
He was opposed by General Douglas MacArthur, commander-in-chief of the South West Pacific Area, who pushed for the invasion of Luzon in the Philippines and argued for bypassing Formosa.
Admiral Raymond Spruance, commanding the Fifth Fleet, concurred with MacArthur that Operation Causeway was unrealistic without further significant reinforcements in the Pacific theater; instead, Spruance proposed the capture of Iwo Jima and Okinawa, the latter an island smaller than Formosa and therefore not requiring additional troops diverted from Europe.
[citation needed] At a high-level meeting in Pearl Harbor in July 1944, President Roosevelt conferred with General MacArthur and Admiral Chester W. Nimitz, Commander-in-Chief of the Pacific Fleet.
‘In San Francisco, Spruance recalled, King continued to argue the case for CAUSEWAY, “but finally gave in and said he would recommend Luzon-Iwo Jima-Okinawa to the Joint Chiefs of Staff in Washington, which he did.” On October 3, the JCS issued new directives sending MacArthur into Luzon in December 1944, the marines into Iwo Jima in January 1945, and a large combined navy-army-marine force into Okinawa in March 1945.