With the introduction of President Sukarno's guided democracy in the late 1950s, SOBSI was formally recognised and given a place in the national decision-making structures.

After the 1965 coup that subsequently produced Suharto's New Order regime, SOBSI was declared illegal, its members killed and imprisoned and most of the leadership executed.

[9] Foreign guests at the Malang congress included two Australians, Ted Roach and Mike Healy, and two Dutch trade unionists, Blokzijl (of Eenheids Vakcentrale) and RKN Vijlbrief.

Suurhof (of Nederlands Verbond van Vakvereenigingen) and Evert Kupers, in his capacity as the vice-chairperson of World Federation of Trade Union, were attending the congress as well.

Rajkni Tomovic (Yugoslavia), Jean Lautissier (France) and Olga Tchetchekina (Russia) of the WFTU were also present.

The Dutch press argued that the SOBSI congress indicated a strong communist influence in the Indonesian labour movement.

[14][15] Until the Madiun Affair, a communist uprising in September 1948, SOBSI was the sole relevant trade union force in the country.

[20] In November 1950 Njono, then 28 years old, returned from a prolonged study trip to China and overtook the leadership of SOBSI as its chairman.

[21] Notably, whilst no longer holding monopoly over the trade union sector, SOBSI was far better organized and financed than its rivals.

[22] Between 1950 and early 1952, SOBSI attempted to mobilize militant actions, raising issues such as wages, social security and workplace conditions.

The Sarbupri strike resulted in the first major victory for SOBSI, having forced the government to significantly increase the estate workers' minimum wage.

Strikes by oil workers in the same year blocked plans for lay-offs and forces the government to institute a non-contributory pension scheme instead.

[24] Following the issue of the ban, SOBSI turned to sporadic strikes and sabotage actions (such as destroying cargo at ports or crops at plantations).

The meeting adopted a new constitution for SOBSI, void of any mention of "socialism", "people's democracy", "class struggle" and "democratic centralism".

Under the new orientation SOBSI sought to build alliances with the peasantry and non-comprador bourgeoisie for popular democratic revolution and to mobilize resistance against imperialism.

In direct contradiction to its earlier line, SOBSI even pledged to help national capitalists and to increase productivity in industries.

[30] In July 1952 the sugar workers union SBG held a major strike demanding Lebaran bonus.

[7] During 1955 SOBSI was able to achieve the implementation of some of its long-running demands, such as introduction of Lebaran bonus, new wage scale for workers and employees in the public sector and distribution of cheap essential goods in some enterprises.

[25] On March 18, 1957 SOBSI organized a 24-hour general strike in south Sumatra, protest against the local take-over of power by a regional army commander.

When Sukarno appointed a 45-member National Council on July 12, 1957, with the task of assisting the cabinet, SOBSI was awarded one seat (represented by Munir).

[28] In the wake of the nationalizations, inter-island shipping services were disrupted and thousands of seamen and harbour workers were left unemployed.

[41] Many high-ranking officers were included in the management boards of nationalized companies, and were hostile to the SOBSI influence in the state enterprises.

[42][45] The army and the Minister of Labour had plans of creating a sole trade union federation in the country, as a way of disarming SOBSI.

In response to the attacks on SOBSI by army elements in state enterprises, PKI began denouncing them as 'bureaucratic capitalists'.

[39][42] SOBSI stepped up its militant opposition against the 'bureaucratic capitalists' in 1960, in response to the abolishing of various colonial-era benefits (such as the Lebaran bonus) in state enterprises.

[40] In December 1963 the United States decided to expand the area of operations of its Seventh Fleet to the Indian Ocean.

[49] Njono left his post as SOBSI chairman in September 1964, as he was assigned to lead the Greater Jakarta organization of PKI.

[54] At Solo and other cities in Central Java railway workers went on strike to prevent the arrival of RPKAD shock troops.

[43] Under the New Order regime, government discourse would continue to argue that independent labour organizing and communism was intimately linked.

[66][68][69] As part of the new national united front line adopted in 1952, SOBSI began organizing frequent joint delegations with other Indonesian unions to countries of the Socialist Bloc.