Final answer:
Japan has protected itself after the war through various means, such as military reserves, police force, and alliances. US military bases in Japan also contribute to its protection.
Step-by-step explanation:
After World War II, Japan was left with minimal defenses. To protect itself, Japan has taken several measures. Firstly, its military reserves provide protection by maintaining a well-trained and equipped military force. Secondly, the police force acts as a protective force by maintaining law and order within the country. Thirdly, the presence of US military bases in Japan provides additional protection, as these bases serve as a deterrent and strengthen Japan's defense capabilities. Finally, while not explicitly mentioned in the given options, it is worth noting that Japan has also strengthened its alliances and cooperation with other countries, particularly with the United States, to ensure its security and protection.
Learn more about Japan's post-war protection measures