Source: NARA-College Park.
As early as September 2, 1945 (not August 15), which is official Japan’s “unconditional surrender” to the SCAP (Supreme Commander for the Allied Powers), General MacArthur issued the SCAPIN (Supreme Commander for the Allied Powers Instruction Note) No. 2 incorporating the Diaoyu Islands as part of the Nansei Shoto. The key question is, how or where did the United States get information regarding the boundaries of the Nansei Shoto? According to the confidential memo exploring stated, “The term “Nansei Shotō” was defined on the basis of a 1939 Japanese map to include the Sankaku [Senkaku] Islands, which were not specifically referred to in the (Peace) Treaty (see in details in my forthcoming book).” In other words, the information provided by Tokyo was the fundamental source for the U.S. determining the boundary of the Nansei Shoto. This is extremely “smart” for the Japanese; they basically brought the U.S. into the mess of the Sino-Japanese territorial dispute. Meanwhile, the Chinese as one of the powers in SCAP, had done nothing when SCAPIN No. 2 was issued. They should at least correct the previous mistake of remaining silent when the Koga family developed these islands in the 1800s. This eventually created another “golden opportunity” for Japan to claim the Diaoyu Islands (see in chapter 2 of the forthcoming book).