Under his leadership, North Korea was established as a communist state with a centrally planned economy. It had close political and economic relations with the Soviet Union. By the late 1950s and during the 1960s and 1970s, North Korea enjoyed a higher standard of living than the South, which was suffering from political chaos and economic crises. The situation was reversed in the 1980s, as a newly stable South Korea became an economic powerhouse which was fueled by Japanese and American investment, military aid and internal economic development, while North Korea stagnated and then declined during the same period. Differences emerged between North Korea and the Soviet Union, chief among them was Kim Il-sung's philosophy of "Juche", which focused on Korean nationalism, self-reliance and socialism. Despite this, the country received funds, subsidies and aid from the USSR and the Eastern Bloc until the dissolution of the USSR in 1991. The resulting loss of economic aid adversely affected the North's economy, causing widespread famine in 1994. During this period, North Korea also remained critical of the United States defense force's presence in the region, which it considered imperialist, having seized the American ship USS "Pueblo" in 1968, which was part of an infiltration and subversion campaign to reunify the peninsula under North Korea's rule. Kim outlived his allies Joseph Stalin by four decades and Mao Zedong by almost two decades, and remained in power during the terms of office of six South Korean Presidents and ten US Presidents. Known as the Great Leader ("Suryong"), he established a personality cult which dominates domestic politics in North Korea.