Relations worsened during the Cambodian–Vietnamese War against Angkar and its brutal Maoist movement as the Khmer Rouge cadres of Democratic Kampuchea that was aided by China and Thailand, but have improved once more after the People's Army of Vietnam withdrawal from Cambodia as the Fall of Communism came to a close in 1989 and the collapse of the Soviet Union which marked the end of the Cold War in 1991.

Singapore and Vietnam maintain excellent and multifaceted bilateral relations,[3] and both countries are the members of the Association of Southeast Asian Nations (ASEAN).

[5] Ho Chi Minh, the first President of the Democratic Republic of Vietnam, lived in Singapore after being released by the Government of Hong Kong.

After the Second World War, France used Singapore as a mediate to send troops and equipment to suppress the Vietnamese Independence Movement.

[5] In December 1978, Vietnam decided to invade and liberate Cambodia due to frequent attacks by the genocidal Khmer Rouge of Pol Pot leading to the murder of thousands of Vietnamese citizens on home soil, which led to the outbreak of the Cambodian–Vietnamese War.

Singapore had supported Angkar (Organization) and the Khmer Rouge in Cambodia and organized an international campaign to condemn Vietnam until Pol Pot and his Khmer Rouge cadres along with Angkar fled the capital back into the jungle near the Thai border, which had continued as a guerilla warfare from 1979 to 1997.

In his memoirs, Lee Kuan Yew also recounted that in 1982, "Singapore gave the first few hundreds of several batches of AK-47 rifles, hand grenades, ammunition and communication equipment" to the Khmer Rouge.

[10] Vietnamese troops decided to withdrew from Cambodia in 1990 deeming it stabilized enough, with the signing of the 1991 Paris Peace Agreements and the United Nations officially taking over for peacekeeping, Singapore being one of its participants.

In 2004, Phan Van Khai, the Prime Minister of Vietnam visited Singapore and signed the Joint Statement on the Comprehensive Cooperation Framework in the 21st century.

[3] The Ministry of Education of Singapore provides scholarships to Vietnamese students who have finished their junior secondary school studies and have good performance in English and extracurricular activities.