companies to broaden their economic cooperation with the DPRK. Under Prime Minister Kakuei Tanaka, the Japanese government adopted a policy of equidistance toward North Korea and South Korea, and refused to take sides with Seoul against Pyongyang during the Mun Se-gwang affair. Nevertheless, it still refrained from establishing diplomatic relations with North Korea. Under Takeo Miki and his successors, Japan switched back to a policy that clearly favored the ROK over the DPRK. The North Korean leadership felt increasingly isolated when Takeo Fukuda concluded the Treaty of Peace and Friendship between Japan and the People's Republic of China, and Yasuhiro Nakasone visited South Korea in 1983. In periods of Japanese-ROK cooperation and Japanese-DPRK friction, Pyongyang often expressed its dissatisfaction by raising the issue of the Liancourt Rocks dispute. Until the late 1980s, North Korea's policy toward Japan was mainly aimed at minimizing cooperation between South Korea and Japan, and at deterring Japan's rearmament while striving for closer diplomatic and commercial ties with Japan. Crucial to this policy was the fostering within Japan of support for North Korea, especially among the Japanese who supported the Japanese communist and socialist parties and the Korean residents of Japan. Over the years, however, North Korea did much to discredit itself in the eyes of many potential supporters in Japan. Japanese who had accompanied their spouses to North Korea had endured severe hardships and were prevented from communicating with relatives and friends in Japan. Japan watched with disdain as North Korea gave safe haven to elements of the Japanese Red Army, which Japan designates as a terrorist group. North Korea's inability or refusal to pay its debts to Japanese traders also reinforced popular Japanese disdain for North Korea. Japan–North Korea relations turned more antagonistic in the late 1980s. The two governments did not maintain diplomatic relations and had no substantive contacts. The opposition Japan Socialist Party nonetheless had cordial relations with the North Korean regime. Japan allowed trade with North Korea only through unofficial channels, reportedly exceeding US$200 million annually in the 1980s. Issues in Japan–North Korea relations that produced tensions included North Korean media attacks on Japan, Japan's imposition of economic sanctions on North Korea for terrorist acts against South Korea in the 1980s, and unpaid North Korean debts to Japanese enterprises of about $50 million. As of 2017, Japan–North Korea relations are at an all-time low after North Korea, on two separate occasions,