After the war between China and Japan, during the occupation of Japan, Prime Minister Shigeru Yoshida (officially the last prime minister under the royal decree by the Japanese emperor), intended to approach the newly established People's Republic of China economically and diplomatically. However, the US rectified this initiative and threatened to boycott the 1951 Treaty of San Francisco if Japan did not engage with KMT-led Nationalist China (now Taiwan) and the later formation of the Treaty of Taipei (a parallel treaty to the Treaty of San Francisco between Japan and the two Chinas that were excluded). The US required Japan to accept diplomatic relations with the KMT-led Nationalist China; otherwise, sovereignty to the country would not be restored, effectively maintaining war with the US and keeping it under US military occupation.