Japan–South Korea relations
Japan–South Korea relations (; ) refers to the diplomatic relations between Japan and the Republic of Korea. As both nations are separated by the Sea of Japan and the Korea Strait, Korean-Japanese interactions have existed since ancient times; the southern portion of the Korean Peninsula acted as a closest entryway for Japan to engage in economic trade and cultural exchange to and from mainland Asia. By 1910, Korea would become a colony of Japan until 1945. Shortly after gaining independence, Korea was divided into two states. During the Korean War, Japan took part in aiding South Korea by providing military supplies to US and UN forces against the communist-led North Korea. Japan and South Korea formally established diplomatic relations in December 1965, under the Treaty on Basic Relations between Japan and the Republic of Korea, with Japan recognizing South Korea as the only legitimate government in the Korean peninsula. Japan and South Korea share many cultural, economic, and military ties. Their economies are respectively the second and fourth largest in Asia, and they are both military allies of the United States. Relations, however, are greatly complicated by a number of issues, including territorial claims on Liancourt Rocks and conflicting views