The 1948 declaration of independence by both South and North Korea made Joseon a defunct nation. Those with Joseon nationality were allowed to re-register their nationality to a South Korean one; however the same did not apply to North Korea due to the fact that Japan only recognises South Korea as the legitimate government of Korea, so supporters of the North retained their Joseon nationality. Ethnic Koreans in Japan established the Association of Koreans in Japan in 1945, which followed a socialist ideology, and was banned in 1949 by the order of Allied occupation army. The United Democratic Front of Korea in Japan was established in 1951, which was banned due to suspected involvement in the 1952 May Day riots. In 1952, the North Korean leader Kim Il-Sung called on the socialist zainichi Korean movement to be coordinated in close contact with the North Korean government, and to fight, not for a socialist revolution in Japan, but for the socialist reunification of the Korean peninsula. Chongryon was established on May 25, 1955 by Han Duk-su, who was an activist for leftist labor movements in Japan. (The pro-South Mindan had already branched off from the main organisation in 1946). In the late 1950s, Chongryon conducted a campaign to persuade Zainichi Koreans to migrate to North Korea. The campaign was vehemently opposed by Mindan which organised hunger strikes and train obstructions. Some 87,000 Zainichi Koreans and about 6000 Japanese spouses moved to the North. According to a defector, himself a former returnee, many petitioned to be returned to Japan and in response were sent to political prison camps. Japanese research puts the number of Zainichi Korean returnees condemned to prison camps at around 10,000. In 1990 Su-to Ha, former vice chief of organization for Chongryon who was expelled in 1972 for demanding democratic reforms, led a rally in Tokyo of 500 to protest against North Korea's human rights violations, in which protesters accused North Korea of holding the ex-Zainichi returnees captive in order to siphon money off remittances from their relatives in Japan. The South Korean National Election Commission considered preventing Chongryon residents from voting in the 2012 South Korean Presidential Election. The North Korean Chongryon-affiliated "Fukushima Korean School" sheltered 18 Japanese citizens from March 18 until the end of March. However, the Chongryon criticized the Ministry of Foreign Affairs of Japan for not officially recognizing North Korea as one of the countries that sent humanitarian aid to the survivors of the 2011 Tōhoku earthquake and tsunami.