Military Coup Prediction

Binary indicator: an illegal and overt attempt by the military or other elites within the state apparatus to unseat the sitting executive. Following Powell & Thyne (2011), includes both successful and failed attempts. Excludes popular revolutions, civil wars, and foreign invasions unless led by domestic military/elite actors.

Binary indicator: a coup attempt that successfully results in the displacement of the incumbent chief executive and seizure of executive power for at least 7 days. Subset of coup_attempt. Success rate globally ~50% across 1950-2010 period.

Logged real GDP per capita as a structural predictor of coup risk. Lower income levels are robustly associated with higher coup probability — the 'coup trap' mechanism where poverty creates grievances and lowers opportunity costs of plotting. One of the most robust predictors across studies (Londregan & Poole 1990, Gassebner et al. 2016).

Short-term negative deviation in GDP growth rate, typically measured as annual real GDP growth or growth relative to trend. Sudden economic downturns increase coup risk by creating popular discontent, weakening regime legitimacy, and reducing the regime's ability to buy military loyalty through patronage.

Military expenditure as a percentage of GDP or total government expenditure. Has theoretically ambiguous effects on coup risk: higher spending may buy military loyalty and reduce grievances, but also empowers the military as an institution and increases its capacity to act. Empirical evidence is mixed (Gassebner et al. 2016).

Number of years since the last regime transition (3+ point Polity score change). Longer-lived regimes face lower coup risk due to institutional consolidation, established patronage networks, and routinized civil-military relations. New regimes are vulnerable during transition periods.

Count or recency of prior coup attempts in a country. The single strongest predictor of future coups — the 'coup trap' dynamic where initial coups lower the normative and practical barriers to subsequent attempts. Countries with recent coup histories face 3-5x higher coup risk than countries without. Operationalized as binary (any prior coup), count, or years since last coup.

The degree to which the ethnic composition of the military (especially officer corps) diverges from the general population. Ethnic homogeneity in the military (via ethnic stacking) may increase loyalty to the regime but creates grievances among excluded groups that can fuel civil war (Roessler 2011, Harkness 2014).

The degree to which the armed forces operate independently from civilian political control. High military autonomy — separate intelligence apparatus, independent budget authority, professional promotion criteria, corporate identity — increases both the capability and motivation for military intervention in politics. Reduced by coup-proofing but at the cost of military effectiveness.

The deliberate appointment of co-ethnics or loyalists to key command positions in the military and security forces. A form of coup-proofing that increases short-term regime security by ensuring military leaders share identity-based loyalty with the ruler, but creates long-term instability by generating grievances among excluded ethnic groups and degrading meritocratic military performance (Harkness 2014, Roessler 2011).

The creation of multiple, competing armed bodies (presidential guards, paramilitaries, intelligence agencies with arrest powers) with overlapping jurisdictions. A key coup-proofing mechanism that prevents any single military unit from accumulating enough power to execute a coup. Reduces coup risk but fragments the security apparatus and degrades conventional military effectiveness.

Regional diffusion or demonstration effects whereby coups in neighboring or culturally similar states increase coup risk domestically. Mechanisms include: (1) demonstration that coups are feasible, (2) diffusion of coup-facilitating networks among military officers trained together, (3) regional instability creating permissive international environments. Operationalized as count of coups in neighboring states or regional coup rate.

External military assistance (arms transfers, training, financial support) provided to a state's armed forces. Theoretically ambiguous effect on coup risk: may professionalize the military and increase civilian control, but may also empower the military and create dependencies that make aid withdrawal destabilizing. Cold War-era aid was often coup-permissive.

Binary indicator for the Cold War period (pre-1991). Coup rates were substantially higher during the Cold War when superpower competition created permissive environments for military intervention. Post-Cold War democratic norms, international organizations, and conditional aid reduced the international tolerance for coups. Structural break in coup patterns around 1991.

Mixed regime type (Polity score approximately -5 to +5) that combines elements of democracy and autocracy. Anocracies face elevated coup risk compared to both full democracies and consolidated autocracies — the 'inverted U' hypothesis. Partial liberalization creates political competition without establishing strong civilian control institutions.

Number of years the current chief executive has been in power. Non-linear relationship with coup risk: new leaders face high risk during consolidation period, risk declines as they establish control and patronage networks, but may rise again in very long tenures as succession anxieties emerge and loyalty networks calcify.

Model-generated probability of a coup attempt occurring in a given country-year. Produced by statistical or machine learning models using structural, institutional, and contextual predictors. Examples include PITF models, ViEWS system (Hegre et al. 2019), and various logistic regression/random forest approaches in the literature.

Using extreme bounds analysis on 60+ proposed coup determinants, the most robustly significant predictors of coup attempts are: (1) past coup history, (2) low GDP per capita, (3) low economic growth, (4) regime type (anocracy), and (5) military regime incumbent. These survive specification changes across hundreds of model permutations.

Coup history is the single most robust predictor of future coups. Countries that have experienced at least one prior coup face dramatically elevated risk, consistent with the 'coup trap' hypothesis where initial coups lower normative and practical barriers to subsequent attempts.

Military spending as a share of GDP does not robustly predict coup attempts. The variable fails to survive extreme bounds testing, suggesting its theoretical ambiguity (buying loyalty vs. empowering military) is reflected in inconsistent empirical results.

Personal rulers in Africa face a strategic dilemma: including rival ethnic elites in government reduces coup risk but increases insurgency risk, while excluding them raises coup risk from within the regime. Ethnic exclusion from the military and government significantly predicts both coup attempts and civil war onset.

Military dictatorships emerge when the military is sufficiently strong relative to civilian institutions and when civilian governments cannot credibly commit to adequate military budgets. The model predicts that higher inequality and weaker democratic institutions increase the probability of military intervention.

Ethnic stacking of the military — the deliberate appointment of co-ethnics to key command positions — is a widespread practice in post-colonial states. While it reduces the risk of military disloyalty to the incumbent, it creates a structurally fragile military that is vulnerable to ethnic counter-mobilization and civil war.

Coup-proofing strategies (parallel security forces, ethnic stacking, rotation of commanders) explain military responses during the Arab Spring: armies in coup-proofed states (Syria, Bahrain) remained loyal while non-coup-proofed militaries (Egypt, Tunisia) defected or facilitated regime change.

Pro-government militias serve as a coup-proofing mechanism beyond the standard strategies. Regimes facing coup risk are more likely to create or maintain militia forces that can counterbalance the regular military, providing an additional layer of regime security.

In dictatorships, the presence of a ruling party with institutionalized power-sharing mechanisms reduces coup risk. Regimes with stronger party institutions can credibly commit to sharing spoils with military elites, reducing their incentive to seize power through coups.

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