Question: When did the manufacturer of Koksan split from the country where Sajik Arena is located?

full_context: Document 1: BJK Akatlar Arena: BJK Akatlar Arena is a multi-purpose indoor arena located in Akatlar, Istanbul, Turkey. The arena is the home court of Beşiktaş J.K.; it also serves the volleyball team. It is also suitable to host other events, such as concerts.
Document 2: AEK-971: The AEK-971 is a Russian (formerly the Soviet Union) selective fire 5.45×39mm assault rifle that was developed at the Kovrov Mechanical Plant (KMZ) by chief designer Sergey Koksharov in the late 1970s and 1980s (currently manufactured by Degtyarev Plant).
Document 3: Division of Korea: The division of Korea between North and South Korea occurred after World War II, ending the Empire of Japan's 35 - year rule over Korea in 1945. The United States and the Soviet Union each occupied a portion of the peninsula, with the boundary between their zones of control along the 38th parallel.
Document 4: Koksan (artillery): The M-1978 Koksan is a 170 mm self-propelled gun of North Korean design and manufacture. Very little information is available due to the secretive nature of the North Korean government. The designations "M-1978" and "Koksan" were given to the type by American military analysts, as they first became aware of it in that year in Koksan, North Korea.
Document 5: Sajik Arena: The Sajik Arena is an indoor sporting arena located in Busan, South Korea. The seating capacity of the arena is 14,099 and was built in 1985. It is the home arena of the Busan KT Sonicboom, a Korean professional basketball team.
Document 6: Military Demarcation Line: The Military Demarcation Line (MDL), sometimes referred to as the Armistice Line, is the 154 mile - long land border or demarcation line between North Korea and South Korea. On either side of the line is the Korean Demilitarized Zone (DMZ). The MDL and DMZ were established by the Armistice at the end of the Korean War in 1953.
Document 7: Korean War: By mid-1950, North Korean forces numbered between 150,000 and 200,000 troops, organized into 10 infantry divisions, one tank division, and one air force division, with 210 fighter planes and 280 tanks, who captured scheduled objectives and territory, among them Kaesong, Chuncheon, Uijeongbu, and Ongjin. Their forces included 274 T-34-85 tanks, 200 artillery pieces, 110 attack bombers, some 150 Yak fighter planes, 78 Yak trainers, and 35 reconnaissance aircraft. In addition to the invasion force, the North KPA had 114 fighters, 78 bombers, 105 T-34-85 tanks, and some 30,000 soldiers stationed in reserve in North Korea. Although each navy consisted of only several small warships, the North and South Korean navies fought in the war as sea-borne artillery for their in-country armies.
Document 8: Sunan Stadium: Sunan Stadium is a multi-purpose stadium in Pyongyang, North Korea. It is currently used mostly for football matches. The stadium holds 40,000 spectators and opened in 1991.
Document 9: Korean War: The Demilitarized Zone runs northeast of the 38th parallel; to the south, it travels west. The old Korean capital city of Kaesong, site of the armistice negotiations, originally was in pre-war South Korea, but now is part of North Korea. The United Nations Command, supported by the United States, the North Korean People's Army, and the Chinese People's Volunteers, signed the Armistice Agreement on 27 July 1953 to end the fighting. The Armistice also called upon the governments of South Korea, North Korea, China and the United States to participate in continued peace talks. The war is considered to have ended at this point, even though there was no peace treaty. North Korea nevertheless claims that it won the Korean War.
Document 10: History of Korea: After the end of WWII in 1945, the Allies divided the country into a northern area, protected by the Soviets, and a southern area protected primarily by the United States. In 1948, when the powers failed to agree on the formation of a single government, this partition became the modern states of North and South Korea. The peninsula was divided at the 38th Parallel: the ``Republic of Korea ''was created in the south, with the backing of the US and Western Europe, and the`` Democratic People's Republic of Korea'' in the north, with the backing of the Soviets and the communist People's Republic of China. The new premier of North Korea, Kim il - Sung launched the Korean War in 1950 in an attempt to reunify the country under Communist rule. After immense material and human destruction, the conflict ended with a cease - fire in 1953. The two nations officially remain at war because a peace treaty was never signed. Both states were accepted into the United Nations in 1991.
Document 11: Division of Korea: The subsequent Korean War, which lasted from 1950 to 1953, ended with a stalemate and has left the two Koreas separated by the Korean Demilitarized Zone (DMZ) up to the present day.
Document 12: Nuclear weapon design: In 1999, nuclear weapon design was in the news again, for the first time in decades. In January, the U.S. House of Representatives released the Cox Report (Christopher Cox R-CA) which alleged that China had somehow acquired classified information about the U.S. W88 warhead. Nine months later, Wen Ho Lee, a Taiwanese immigrant working at Los Alamos, was publicly accused of spying, arrested, and served nine months in pre-trial detention, before the case against him was dismissed. It is not clear that there was, in fact, any espionage.
Document 13: Busan Exhibition and Convention Center: Busan Exhibition and Convention Center (), commonly known as BEXCO (Busan EXhibition and Convention center), is a convention and exhibition center located in Centum City, Haeundae-gu, Busan, South Korea. It features over 46,500㎡ of exhibition space and 53 meeting rooms. In June 2012, BEXCO completed its expansion to add a 4,002 seat auditorium and a new exhibition center.
Document 14: Pyongyang Gymnasium: Pyongyang Gymnasium, also known as Pyongyang Indoor Stadium, is an indoor sporting arena located in Pyongyang, North Korea. The capacity of the arena is for 20,100 people and was opened in 1973. It is used to host indoor sporting events, such as basketball and volleyball, as well as concerts.
Document 15: KM-SAM: The KM-SAM is the middle-tier of South Korea's three-tier aerial and missile defense system. Though it was developed in Russia by the Almaz Design Bureau with assistance from Samsung Thales, LIG Nex1, and Doosan DST, localization and industrialization were done in South Korea enough to consider it an indigenous system. The Cheongung (Iron Hawk) can intercept targets up to an altitude of at a range of . It is to replace upgraded MIM-23 Hawk batteries in South Korea and be made available for export. Almaz-Antey continued with the program after prototypes were transferred and have created a distinctly Russian version called the Vityaz missile system.
ground_truth: 1953
sub_queries: Koksan >> manufacturer Answer: North Korea
Sajik Arena >> country Answer: South Korea
when did North Korea split from #2 Answer: 1953