Japan's postwar security was founded on Article 9 of the Japanese Constitution.
It renounces the use of force as a tool for foreign policy. This has resulted in a Japan that is primarily engaged in regional and global relations through overseas development aid, foreign direct investment and a strong focus on building relationships via diplomacy based on trade, infrastructure, connectivity and culture.
These tools have worked well for like-minded countries, but this strategy or this process has not accrued the kinds of benefits that Japan needs in order to preserve its security within its backyard.