The fourth National Party Congress is held from December 14-20, 1976 in Hanoi. (Photo: VNA) 
Thong Nhat train from Ho Chi Minh City arrives in Hanoi in the happiness of the capital city’s people, officially marking the launch of the North-South rail route, Jan. 4, 1977. (Photo: VNA) 
Prime Minister Pham Van Dong and Lao Prime Minister Kaysone Phomvihane sign the Vietnam-Laos Treaty of Amity and Cooperation in Vientiane, July 18, 1977. (Photo: VNA) 
Vietnam joins the United Nations on September 20, 1977. This is a historical milestone, marking the world’s largest organisation and international community’s recognition of Vietnam, a peaceful, united, independent, free and democratic country. (Photo: VNA) 
Party General Secretary Le Duan, Prime Minister Pham Van Dong and General Secretary of the Soviet Communist Party Central Committee sign the Vietnam-Soviet Treaty of Friendship and Cooperation in Kremlin Palace in Moscow, November 4, 1978. (Photo: VNA Archives) 
Soldiers fight in the southwestern border battle field, 1978. (Photo: VNA Archives) 
Public security forces join in defending the Dong Dang fortress in Lang Son during the northern border defence war, February 1979. (Photo: VNA) 
Acting President Nguyen Huu Tho signs an order to announce the new Constitution, December 1980. (Photo: VNA) 
Vietnamese astronaut Pham Tuan and Soviet Union cosmonaut Viktor Gorbatko make a spaceflight at 21:33:3 (Moscow time) on July 23, 1980 under the Vietnam-Soviet Intercosmos cooperation programme. (Photo: VNA) VNA
