From 1965 to 1989, the government occasionally reported police actions targeting small subversive organizations. However, at no time were any of these groups considered a significant threat to the Lee government. From 1968 to 1974, a group known as the Malayan National Liberation Front carried out occasional acts of terrorism in Singapore. In 1974 the Singapore Police Force's Internal Security Department arrested fifty persons thought to be the leading members of the organization. After police interrogation, twenty-three of the fifty persons arrested were released, ten were turned over to Malaysia's police for suspected involvement in terrorist activities there, and seventeen were detained without trial under the Internal Security Act. One leader subsequently was executed in 1983 for soliciting a foreign government for weapons and financial support. The government alleged the Malayan National Liberation Front had been a front organization of the CPM, which in the late 1980s was still operating in the border area of northern Malaysia and southern Thailand.

In 1982 a former Worker' Party candidate for Parliament and fourteen of his associates were arrested for forming the Singapore People's Liberation Organization. Zinul Abiddin Mohammed Shah, who had run unsuccessfully for Parliament in the 1972, 1976, and 1980 elections, was accused of distributing subversive literature calling for the overthrow of the government. Shah was tried and convicted on this charge in 1983 and was sentenced to two years in jail. His associates were not prosecuted.

In 1987 twenty-two English-educated professionals were arrested under the Internal Security Act for their alleged involvement in a Marxist group organized to subvert the government from within and promote the establishment of a communist government. For reasons unknown, the Marxist group had no name or organizational structure. The government accused those arrested of joining student, religious, and political organizations in order to disseminate Marxist literature and promote antigovernment activities. Although twenty-one of the twenty-two persons arrested were released later that year after agreeing to refrain from political activities, eight were rearrested in 1988 for failing to keep this pledge. According to a 1989 Amnesty International report, two persons were being detained in prison without trial under Section 8 of the 1960 Internal Security Act. This number represented a significant reduction from the estimated fifty political prisoners held in 1980 (see Political Opposition, ch. 4).

In January 1974, four terrorists belonging to the Japanese Red Army detonated a bomb at a Shell Oil Refinery on Singapore's Pulau Bukum and held the five-man crew of one of the company's ferry boats hostage for one week. The incident tested Singapore's capability to react to a terrorist attack by a group based outside the country and one having no direct connection with antigovernment activities. The counterterrorist force mobilized by the government after t735 the bombing and hijacking comprised army commando and bomb disposal units and selected air force, navy, and marine police units. Negotiations with the terrorists focused on the release of the hostages in return for safe passage out of the country. Apparently the government's primary consideration was to end the incident without bloodshed if at all possible. The Japanese government became involved when five other members of the Japanese Red Army attacked the Japanese embassy in Kuwait and threatened to murder the embassy's staff unless they and the four terrorists in Singapore were allowed to travel to Aden in the People's Democratic Republic of Yemen (South Yemen). Singapore refused to provide transportation for the terrorists but allowed a Japanese commercial airliner to land in Singapore, pick them up, and fly from Singapore to Kuwait. The hostages were released unharmed, and no deaths or serious injuries resulted from the incident.

Data as of December 1989