Since its inauguration in January 2017, the Trump administration’s America First policy, which seems unhesitant about confronting other parts of the world while paying little attention to the free and open international order it had been leading, has had significant impacts on the international community. The policies of the United States, Japan’s sole ally, have played a central role in building and maintaining the free and open international order in the Indo-Pacific region, which has a direct impact on the security environment and stable economic development of Japan. It is hence critical to understand whether or not the Trump administration will fundamentally change America’s role in the international arena, what domestic changes have brought the Trump administration to power in the United States, and how these changes have been and will be manifested in the Trump administration’s foreign policy.