What measures did Japan take to ensure post-war security?

Japan ensured post-war security through the adoption of a pacifist constitution, reliance on the US for military protection, and economic development.

After World War II, Japan was occupied by Allied forces led by the United States. During this period, Japan adopted a new constitution, known as the "Postwar Constitution" or the "Constitution of Japan", which came into effect on May 3, 1947. This constitution, often referred to as the "Postwar Constitution" or the "Constitution of Japan", is best known for its Article 9, in which Japan renounces the sovereign right of belligerency and aims at an international peace based on justice and order. This effectively meant that Japan could not engage in war or maintain a military for warfare, thereby ensuring its security through pacifism.

In addition to the pacifist constitution, Japan's security was also guaranteed by the United States through the Treaty of Mutual Cooperation and Security between the United States and Japan. Signed in 1960, this treaty committed the US to defend Japan in the event of an attack, and allowed the US to maintain military bases in Japan. This reliance on the US for military protection has been a key aspect of Japan's post-war security strategy.

Economic development was another measure taken by Japan to ensure its post-war security. The Japanese government implemented a series of economic policies that resulted in rapid industrialisation and economic growth, known as the "Japanese economic miracle". By transforming itself into an economic powerhouse, Japan was able to increase its international standing and influence, thereby enhancing its security.

Furthermore, Japan has also pursued a policy of diplomatic engagement and has been an active participant in international organisations such as the United Nations. This has allowed Japan to build strong diplomatic ties with other countries and to play a role in global decision-making processes, further contributing to its post-war security.

In recent years, there has been debate in Japan over whether to amend the pacifist constitution to allow for a more proactive role in international security, in response to changing security dynamics in East Asia. However, any such changes would be highly controversial and would require careful consideration of Japan's post-war security measures and their implications.