An independent kingdom for much of its long history, Korea was occupied by Japan beginning in 1905 following the Russo-Japanese War. Five years later, Japan formally annexed the entire peninsula. Following World War II, Korea was split with the northern half coming under Soviet-sponsored communist control. After failing in the Korean War (1950-53) to conquer the US-backed Republic of Korea (ROK) in the southern portion by force, North Korea (DPRK), under its founder President KIM Il Sung, adopted a policy of ostensible diplomatic and economic "self-reliance" as a check against outside influence. The DPRK demonized the US as the ultimate threat to its social system through state-funded propaganda, and molded political, economic, and military policies around the core ideological objective of eventual unification of Korea under Pyongyang's control. KIM Il Sung's son, KIM Jong Il, was officially designated as his father's successor in 1980, assuming a growing political and managerial role until the elder KIM's death in 1994. KIM Jong Un was publicly unveiled as his father's successor in 2010.