Despite their Sinospheric and socialist background, centuries of conquest by modern China's imperial predecessor as well as modern-day tensions have made relations wary.

He proclaimed himself An Dương Vương ("King An Dương"), renamed his newly acquired state from Văn Lang to Âu Lạc and established the new capital at Phong Khê (now Phú Thọ, a town in northern Vietnam), where he tried to build Cổ Loa Citadel, the spiral fortress approximately ten miles north of his new capital.

[9][10] The Chinese military leader Zhao Tuo founded the Triệu dynasty, which ruled Nanyue in southern China and northern Vietnam.

China had planned to spread massive propaganda on the Atlantic Charter and Roosevelt's statement on Vietnamese self-determination to undermine the French authority in Indochina.

[15] After the Second World War ended, a United Nations mandate, had 200,000 Chinese troops, led by General Lu Han, sent by Chiang Kai-shek to Indochina north of the 16th parallel with the aim of accepting the surrender of the Japanese occupying forces.

[26] During the 1954 Geneva Conference ending the First Indochina War, Chinese premier Zhou Enlai urged the Viet Minh delegation to accept partition at the 17th parallel, which was regarded as a betrayal.

[30]: 29  The communist party also expanded the campaign into cultural media such as film and photography exhibitions, singing contests, and street performances.

Those issues included the lack of delineation of Vietnam's territorial waters in the Gulf of Tonkin and the question of sovereignty over the Paracel and Spratly Islands in the South China Sea.

[citation needed] Sporadic fighting on the border occurred throughout the 1980s, and China threatened to launch another attack to force Vietnam's exit from Cambodia.

[33] In 2002, Jiang Zemin made an official visit to Vietnam in which numerous agreements were signed to expand trade and co-operation and to resolve outstanding disputes.

[38] Both leaders released a joint statement, calling for cooperation in economic, political, defense and security areas and working together in “the fight against terrorism, ‘peaceful evolution’, ‘colour revolution’ and the politicisation of human rights issues”.

[38] Vietnamese prime minister Phạm Minh Chính visited China in June 2023 to attend a summit of the World Economic Forum.

[42] On 13 October 2024, Vietnam and China signed 10 agreements to boost cross-border rail links, payment systems, and economic cooperation, while also enhancing defense and trade relations.

[29]: 95  A second round of negotiations in August 1978 was also unsuccessful because of the Youyi Pass Incident in which the Vietnamese army and police expelled 2,500 refugees across the border into China.

China had previously voiced its disagreement over Vietnamese oil exploration in the area, stating that the Spratly Islands and the surrounding waters were its sovereign territory.

[55] Defense of the South China Sea was cited as one of the possible missions of the first Chinese PLA Navy aircraft carrier, the Liaoning, which entered service in September 2012.

"[57][29]: 228  A month afterwards, China enacted a previously delayed plan established prefecture of Sansha City,[29]: 228  which encompassed the Xisha (Paracel), Zhongsha, and Nansha (Spratly) Islands and the surrounding waters.

Other countries surrounding the South China Sea have claims to the two island chains, including Taiwan, Brunei, Malaysia, and the Philippines.

Nobuo Kishi signed an accord that Japanese-made defense equipment and technology are to be exported to the Southeast Asian country, and to boost cooperation amid worries of China's actions.

[64] In recent years, Beijing oversaw the replacement of traditional Chinese wooden fishing vessels with steel-hulled trawlers, fitted with modern communication and high-tech navigation systems.

[citation needed] In May 2014, both countries sparred over an oil rig in disputed territory in the South China Sea, which triggered deadly anti-Chinese protests in Vietnam.

[67] Following the damage, the Vietnamese government pursued a more moderate foreign policy approach with China and sought to improve the bilateral relations.

[69] In 2014, a survey conducted by the Pew Research Center showed 84% of Vietnamese were concerned that disputes relating to the South China Sea could lead to military conflict.

[74] In late 2020, Chinese Defense Minister Wei Fenghe met with Vietnamese ambassador to China Phạm Sao Mai in an attempt to cool down tensions after an increased number of incidents.

[75] The Vietnamese strategy on the South Chinese Sea disputes has been described as a long term consistent act of "balancing, international integration and 'cooperation and struggle'.

[77][78][79] Illegal border crossings by Chinese nationals was linked by the Vietnamese public as the perceived cause of new COVID-19 infections in Vietnam, although there had been no evidence for this.

[80][81] In May 2020, an Israeli cybersecurity company reported to have discovered ransomware attacks targeting government systems in Vietnam and several other countries by China-linked groups.

[82] In August 2021 shortly before an expected visit by US Vice President Kamala Harris, Vietnamese Prime Minister Pham Minh Chinh reassured Xiong Bo, the Chinese envoy to Hanoi that Vietnam will not enter an alliance to counter China.

Xiong stated in the meeting that the two communist nations shared the same political system and beliefs and that China was willing to work with Vietnam and stick to the two countries’ high-level strategic directive to further develop ties.

[86] The agreements addressed a variety of issues, including cross-border rail development, digital infrastructure, and establishing joint patrols in the Gulf of Tonkin and a hotline to handle South China Sea fishing incidents.