According to the Joint Chiefs of Staff, how likely was Japan to surrender unconditionally?

Dontmindme As World War II progressed in the Pacific, the Joint Chiefs of Staff (JCS) confronted the prospect that getting an unconditional surrender from Japan might require invading the Japanese homeland. A number of key Navy and Army Air Force officers led by Fleet Admiral Ernest King, Chief of Naval Operations, and General H. H. "Hap" Arnold, Chief of the Army Air Force, argued that a combination of sea blockade and aerial bombardment could produce a Japanese surrender without the need for a ground invasion. Army Chief of Staff Gen. George C. Marshall and his Army planners, however, believed that Japan's surrender on the terms being demanded by the Allies could be assured only by invasion of its home territory. Both sides made legitimate arguments, but the debate also appears to have reflected organizational competition.