After the Second World War, Japan was occupied by the United States, regaining its sovereignty in 1952 with the signing of the San Francisco Peace Treaty and the Japan-US Security Treaty. During the Cold War, Japan maintained a low military profile, refraining from developing strong military forces and from deploying them overseas. Its security relations with East Asian countries were not very tense. However, Japan’s security policy has undergone significant transformation after the Cold War. This change was prompted by the weakening of the left in Japanese domestic politics, North Korea’s missile and nuclear development programmes, and the rise of China’s power. Instead of making active efforts at improving its relations with its neighbouring states, Japan has taken a realist policy of strengthening its own military capability, enhancing its alliance, and building new security ties with states that have similar security concerns.