 As part of decolonisation and increasing British disengagement from Malaya, constitutional talks on self-government for Singapore between the British Colonial Office in London and the Singapore Legislative Assembly had already resulted in the 1958 State of Singapore Constitution, and a fully elected and self-governing 51-seat Legislative Assembly in 1959.Tunku worried that the next round of constitutional talks would grant Singapore even more independence and put the island beyond his or Britain's reach; as British officials put it, a 'batik curtain' would descend across the Straits of Johor, beyond which political elements and possibly even a 'communist Cuba' would gather strength.This fear became increasingly real to Tunku after 29 April 1961 when Ong Eng Guan of the left-wing United Peoples' Party trounced the PAP candidate at the Hong Lim by-election..

Tunku was also worried about Indonesia, the other regional Malay behemoth, which under Sukarno's Guided Democracy was becoming increasingly nationalistic and expansionist, undertaking regional actions such as the liberation of West New Guinea and Konfrontasi (also known as the Borneo confrontation).