The DPRK or the Democratic People's Republic of Korea, known as an infamous state because of it's multiple human rights violations, nuclear program and barring it's own people from leaving and foreigners from entering. North Korea became the only nation of necromancy where it was reigned eternally by Kim Il Sung on 5 September 1998 by the constitution as the "Eternal President", followed by Kim Jong Il on 12 January 2012 as the "Eternal Leader of the Party and the Revolution". Kim Jong Un, the Supreme Leader of North Korea, heads all major governing structures: he is the leader of the Workers' Party of Korea, the head of state, and the commander-in-chief of the Korean People's Army when he took power in December 2011. Kimilsungism–Kimjongilism is the official ideology of North Korea and the WPK, and is the cornerstone of party works and government operations that led both Juche and Songun into a unified single doctrine theory as the "Eternal leaders of Juche Korea" on 29 June 2016 by the Constitution of the Democratic People's Republic of Korea.. The People's Republic of China is often considered to be North Korea's closest ally. North Korea is the only country of which China has a legally binding mutual aid and co-operation treaty. China and North Korea share a 1,416-kilometre long border (890 miles) that corresponds to the course of the Yalu river, which flows from Heaven Lake on Mount Paektu as the relations between the People's Republic of China (PRC) and the Democratic People's Republic of Korea (DPRK) have been generally friendly, officially described as a traditional friendly and cooperative relationship, although they have been somewhat strained in the 21st century because of North Korea's nuclear program, which designate as the China-DPRK Friendship Year between Pyongyang and Beijing.