According to People's Daily Online, the Ministry of Foreign Affairs of Japan revealed there were three secret deals between Japan and the United States out of four alleged deals it has been investigating, including one on the introduction of nuclear weapons into Japan.
In 1960, the two countries signed the Japan-U.S. security treaty and the two countries related to the 1972 reversion of Okinawa to Japanese sovereignty from U.S. control. Moreover, Japan agreed that America can send their troops, in the event of a contingency on the Korean Peninsula, and that Japan promised the United States use of U.S. bases in Japan without prior consultations if an outbreak arose.
Hirofumi Hirano, Japan's chief cabinet secretary said, "Hatoyama administration has tried hard to discover the existence of these secret treaties. And the Japanese people do not trust their government's declaration about foreign affairs; however, the new government is trying hard to get back the people's trust by finding the truth."