Although Japan and South Korea are close in proximity, both bordering the Donghae, and are both major non-NATO allies of the United States, the relationship between the two states has greatly deteriorated in recent years, characterized by strong mutual distrust and a number of disputes. These disputes include: territorial claims on Liancourt Rocks (Dokdo or Takeshima), Japanese prime ministers' visits to Yasukuni Shrine, differing views on Imperial Japan's treatment of colonial Korea, and Japan's refusal to negotiate Korea's demands that it apologize or pay reparations for mistreatment of World War II comfort women from Korea. The Diplomatic Bluebook of Japan by the Ministry of Foreign Affairs of Japan in 2018 removed the phrase present in the previous year referring to the ROK as "Japan's most important neighbor that shares strategic interests with Japan." In 2021, South Korea dropped its description of Japan as a "partner" in its latest defense white paper. These tensions have complicated American efforts to promote a common front against Chinese, Russian, and North Korean threats in the region.Alastair Gale, "Enmity Between South Korea, Japan Worries U.S.: Seoul's demand for new apology over WWII ‘comfort women’ complicates regional security ties", Wall Street Journal, February 17, 2015
