Rajaratnam was Singapore's first foreign minister, following its abrupt independence in 1965. During his tenure as foreign minister, Rajaratnam helped Singapore gain entry into the United Nations and later the Non-Aligned Movement in 1970. He built up the Foreign Service and helped to establish diplomatic links with other countries and secure international recognition of the new nation's sovereignty. He carried out the foreign policy of international self-assertion to establish Singapore's independence during the period when the country faced significant challenges including the Konfrontasi conflict in the 1960s and the withdrawal of British troops in the early 1970s. Rajaratnam was one of the five "founding fathers" of ASEAN in 1967. In this diplomatic arena together with UN he helped to draw international attention to Vietnam's invasion of Cambodia in 1978. Sompong Sucharitkul, an aide of Thailand's then foreign minister Thanat Khoman, conveys Rajaratnam's stance on ASEAN membership for Sri Lanka in 1967: