Final answer:
During the post-WWII US occupation, Japan's military was limited to defensive purposes, and Japan underwent significant demilitarization and democratization led by General MacArthur. The newly formed Japanese Constitution barred Japan from offensive military capabilities and embodied the nation's commitment to pacifism and democracy, culminating in a successful transformation into a US ally.
Step-by-step explanation:
During the US occupation of Japan after World War II, Japan's military was severely restricted to defensive purposes. General MacArthur led the American military presence and supervised significant changes in Japanese society including demilitarization, democratization, and the establishment of respect for human rights. The Japanese Constitution, often referred to as the MacArthur Constitution due to the heavy American influence in its drafting, imposed demilitarization where Japan was barred from maintaining an offensive army and committing to future wars.
An important aspect of political and economic changes included land reforms, encouragement of union membership, and retention of large corporations to facilitate economic recovery. This process also involved cultural reeducation, resulting in Japan renouncing militarism and adopting pacifism as evidenced in their constitution's preamble declaring their desire for eternal peace.
Eventually, the reforms fostered by the US occupation led to Japan's successful transformation into a stable, peace-oriented, and prosperous democracy, strategically aligned as a close ally of the United States in the post-war period. Partnership with Japan was seen not only as a geopolitical success against the spread of communism but also as a hallmark of successful reconstruction and democratization.