Coup Atlas Research Database
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85010171952AttemptedMilitary coup

Indonesia, 1952 — military coup attempt

Indonesia (IDN)Southeast Asia, AsiaOctober 17, 1952

Event Summary

On 17 October 1952 the leaders of the Indonesian Army high command, Chief of Staff Colonel Abdul Haris Nasution and Armed Forces Chief Tahi Bonar Simatupang, mobilized troops and marshaled civilian demonstrators to pressure President Sukarno in what became known as the October 17 affair. The confrontation grew out of a dispute over the army's plan to demobilize tens of thousands of soldiers and professionalize the force, which parliament, siding with traditionalist officers, resisted as excessive civilian meddling in military affairs. The officers surrounded the Merdeka Palace, pointed tank turrets at it, and demanded that Sukarno dissolve the provisional parliament and hold immediate elections.

Sukarno refused, came out and addressed the crowd, and defused the standoff; the army's gambit failed. Nasution and Simatupang were removed from their posts in December 1952, though Nasution was reappointed army chief in 1955 after reconciling with Sukarno.

Researched Details

Researched

Independent research, added record by record. Hover any label for what it means.

Target identified in Coup Atlas research: President Sukarno refused the demands and remained in power; the army leaders were removed but Nasution returned in 1955
RESEARCHED NAME
Key figures
Sukarno (president of Indonesia, target)
Abdul Haris Nasution (army chief of staff, leader)
Tahi Bonar Simatupang (armed forces chief, leader)
Bambang Supeno (traditionalist officer whose dismissal sparked the crisis)

Sources

The 17 October affair was an event in which Indonesian soldiers pressured the president to disband the Provisional People's Representative Council at the behest of the chief of staff and the commander of the armed forces, made while the Merdeka Palace was surrounded, after tensions over army reorganization and civilian meddling culminated in demonstrations mobilized by the army.
SOURCE REVIEWED Wikipedia, 17 October affair open source ↗
On 17 October 1952 Nasution and Simatupang had their troops surround the Presidential Palace and point their tank turrets at it, demanding that the current DPR be dismissed, and Sukarno came out and convinced both soldiers and civilians to go home, defeating them.
SOURCE REVIEWED Wikipedia, Abdul Haris Nasution open source ↗
The affair erupted when Nasution and other senior officers took control of Djakarta and urged Sukarno to dissolve the government, take power into his own hands, and hold immediate national elections, which Sukarno refused.
SOURCE REVIEWED U.S. State Department, FRUS 1958 to 1960 vol. XVII open source ↗
Nasution and Simatupang were questioned by the attorney general and in December 1952 both lost their positions and were discharged, though Nasution was reappointed army chief of staff on 27 October 1955 after three years out.
SOURCE REVIEWED Wikipedia, Abdul Haris Nasution open source ↗

Editorial Note

Exact date match, well documented. The 1952 humiliation shaped Nasution's later drive for army autonomy and his alignment with Sukarno's Guided Democracy after 1957, themes that recur around the 1965 events in the dataset.

Cross-Reference

Only one dataset carries it. One of the three reference datasets we check against carries this event; the others do not list it. That is not a contradiction — the datasets cover different periods and use different thresholds — but it means the record has had less outside corroboration.

Identifiers for finding this same event in the other datasets:

Cline Center id
85010171952

How the match is made is described in crossref-report.md.

Outcome and Target

Coup Atlas research identifies the target as: President Sukarno refused the demands and remained in power; the army leaders were removed but Nasution returned in 1955.

Baseline coding: Coup attempt failed to remove the incumbent. Recorded leader fate: remained in office; not physically harmed. The baseline file does not name individual targets; researched names are kept in a separate layer.

Baseline Dataset Citation

Cline Center Coup d’État Project Dataset, v2.2.2
Peyton, Buddy, Joseph Bajjalieh, Michael Martin, and Andrea Gerald. 2026. Cline Center Coup d’État Project Dataset. Cline Center for Advanced Social Research. V.2.2.2. February 17. University of Illinois Urbana-Champaign. doi: 10.13012/B2IDB-9651987_V10
⚑ This citation establishes the coded baseline record; use the claim-level sources above for the researched narrative.

Baseline Source-Document Entries

CSP

Named in the baseline source document; no article citation was recorded.

Wikipedia

New York Times

“NEW INDONESIA CRISIS SEEN IN ARMY ISSUE,” April 13, 1953

This is the citation trail carried by the baseline dataset, grouped by outlet and rejoined from the line-wrapped original. Coup Atlas has not independently re-checked every document; read the original before citing a specific claim. URLs the import damaged beyond safe repair are shown as plain text and listed in citations-report.md. How this list is built →

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