Gyeongui Line (1904–1945)
Following Japan's defeat in the Pacific War and the subsequent partition of Korea, the Gyeongui Line was divided at the 38th parallel between North and South Korea. On 25 August 1945, the Soviet Army began operating trains on the line north of Sariwon, whilst trains in the south terminated at Gaeseong. In 1946, the railways in both North and South were nationalised, creating the Korean National Railroad in the South and the Korean State Railway in the North. After the Korean War, the Gyeongui Line was split into three sections. In the South, the Seoul–Jangdan section became the KNR's Gyeongui Line, retaining the same name; in the North, the Bongdong–Pyeongyang section became the P'yŏngbu Line, whilst the Pyeongyang–Sinuiju section became the P'yŏngŭi Line.
July 4th North–South Korea Joint Statement
The 7 · 4 South and North Korea Joint Statement, also known as the July 4th North-South Joint Communiqué, was signed on July 4, 1972, by the Republic of Korea and the DPRK government for the first time since the division of the Korean peninsula. In 1972, following the instructions of Park Jung-hee, the director of KOREA-CIA Lee Hu-rak was sent to the Democratic People's Republic of Korea and met with Kim Il-sung to establish three principles of unification: 1) independence, 2) peace and 3) nation-wide unity.
It was enacted to promote international detente, declaration of the withdrawal of the USFK and reduction of Military arms competition. However, after the discussion on unification, the regime of both sides of the two Koreas was unable to proceed with the real action plan because of the instability of their political power in the country.