Amid reports of increased clashes between Vietnamese and Chinese forces along their shared border, on 3 November 1978 Vietnam and the Soviet Union signed a treaty of friendship, further strengthening the ties between the two
Seen together with Vietnam’s recent membership in COMECON, the binding economic organisation under the aegis of the Soviet Union, the treaty of friendship further antagonised the growing deterioration between Chinese and Vietnamese relations.
On 4 November, The Washington Post reported the signing of the treaty of friendship at the Kremlin as a televised event filled with joy and good cheer, showing, Alexei Kosygin, Vietnamese Communist Party Leader Lê Duẩn and Premier Phạm Văn Đồng “embracing, smiling and drinking champagne toasts.” At the party, was quoted as saying that it was “predictable that [the pact] will be resented by those who do not like friendship between Moscow and ,” adding, “the treaty has already become a political reality and whether they want it or not they will have to reckon with this reality.” The strongly worded ultimatum was clearly aimed at China and their increasingly stronger ally, America.
Vietnamese Communist Party Leader Lê Duẩn also made Vietnam’s position clear, quoted by the Soviet Union’s press agency, Tass, declaring that China was “establishing a new alliance with imperialism and fascist hangers-on, an alliance against the socialist system and the movement of national independence.” He was also quoted as saying China was “pursuing a fiercely hostile policy against Vietnam.”
As well as a treaty of friendship, Vietnam and the Soviet Union also signed economic and technical agreements that meant millions of rubles in future aid to. Specifically, the Soviet Union agreed to improve strategic railroad links between , Haiphong and .