The starting probabilities of this template were calculated by asking a narrow outside-view question: if the United States has already crossed the threshold of deploying at least 1,000 troops on the ground in Iran, how long have roughly comparable U.S. ground involvements historically taken to wind down?
This is a relative-time market surface, not a live calendar-date forecast. The current CSV uses a dummy anchor date only so the market can fit Antistatic's :date schema. The meaningful quantities are the elapsed-time labels: rows are weekly thresholds after deployment, while the projection_group buckets are month counts after deployment.
Once a real ≥1,000-troop deployment happens, the market should be restaged by shifting every threshold and end date so that week 1 equals deployment day + 7 days, week 2 equals deployment day + 14 days, and so on. At that point the title should also be de-conditionalized.
Reference Classes and Partial Pooling
The model uses two overlapping duration layers. The first captures limited-duration interventions such as Lebanon 1958, Haiti 1994, or other coercive footholds that end in weeks or months. The second captures major campaigns and occupations such as Korea, Vietnam, Iraq 2003, and Afghanistan, where large ground deployments can persist for years. Some cases sit between these layers. Grenada, Panama, and the Desert Storm ground offensive are counted as overlap cases rather than forcing them into only one bucket.
| Reference layer | Raw cases | Overlap-adjusted effective count | Role in the fit |
|---|
| Limited-duration interventions | 7 | 5.5 | Supplies the short and medium tail: weeks to several months. |
| Major campaigns / occupations | 7 | 5.5 | Supplies the heavy right tail: year-plus entanglement risk. |
Overlap handling is explicit: each case gets total weight 1.0. If a case belongs to both layers, its weight is split evenly across them. That prevents short decisive invasions such as Grenada or Panama from pulling either layer too hard on their own.
The final template uses a 60% limited-duration / 40% major-campaign mixture. That is a relevance-weighted outside-view judgment rather than a raw sample frequency. Equal-weight historical counts would lean too heavily on the handful of twentieth-century occupation wars, while the actual threshold in this question is a ≥1,000-troop deployment. That threshold still leaves a real major-war tail, but it is more compatible with limited coercive occupations than with a full regime-change campaign.
Fitted Duration Distributions
Durations are modeled on log(days after deployment). Each layer borrows a small amount of information from the other to avoid overfitting: the limited-duration layer borrows 10% of its log-mean and log-sigma from the major-campaign layer, while the major-campaign layer borrows 5% from the limited-duration layer. Sigma floors are kept wide so the final curve preserves meaningful uncertainty.
| Layer | Median duration | 75th percentile | 90th percentile |
|---|
| Limited-duration interventions | 136 days | 416 days | 1139 days |
| Major campaigns / occupations | 607 days | 3291 days | 15070 days |
Selected Conditional Probabilities
These are the template's cumulative probabilities for the involvement having ended by the stated elapsed time after deployment.
| Elapsed time | Probability involvement has ended by then |
|---|
| 1 week | 3.7% |
| 2 weeks | 7.8% |
| 4 weeks | 14.6% |
| 8 weeks | 24.7% |
| 12 weeks | 31.8% |
| 16 weeks | 37.2% |
| 24 weeks | 45.2% |
| 36 weeks | 53.2% |
| 52 weeks | 60.2% |
Month Bucket Summary
The projection-group buckets correspond to months after deployment. The probability shown for each bucket below is the probability by the last weekly threshold inside that bucket.
| Bucket | Probability by end of bucket |
|---|
| 1 month | 14.6% |
| 2 months | 24.7% |
| 3 months | 31.8% |
| 4 months | 38.4% |
| 5 months | 42.6% |
| 6 months | 46.0% |
| 7 months | 49.7% |
| 8 months | 52.1% |
| 9 months | 54.3% |
| 10 months | 56.7% |
| 11 months | 58.3% |
| 12 months | 60.2% |
Most Influential Examples
| Start | End | Example | Peak troops | Duration | Why it matters | Source |
|---|
| 1958-07-15 | 1958-10-25 | Lebanon intervention (Operation Blue Bat) | 14,000 | 102 days | Short coercive landing and stabilisation mission; good analogue for a limited U.S. foothold without regime-change occupation. | Office of the Historian: Lebanon, 1958 |
| 1983-10-25 | 1983-11-05 | Grenada invasion opening phase | 7,300 | 11 days | Short, successful invasion at a scale larger than a foothold but much shorter than Iraq- or Afghanistan-style occupations. | Britannica: Grenada invasion |
| 1989-12-20 | 1990-01-31 | Panama invasion (Operation Just Cause) | 26,000 | 42 days | Large but short regime-change operation; relevant overlap case for a high-force deployment with a comparatively quick end-state. | Britannica: Panama invasion |
| 1991-02-24 | 1991-02-28 | Desert Storm ground offensive into Iraq/Kuwait | 270,000 | 4 days | Very short but very large ground campaign; keeps open a fast-end tail even inside the major-force reference layer. | Britannica: Persian Gulf War |
| 1994-09-19 | 1995-03-31 | Haiti intervention (Operation Uphold Democracy) | 20,000 | 193 days | Large U.S. deployment with a months-long stabilisation phase rather than a multiyear war. | Office of the Historian: Intervention in Haiti, 1994-1995 |
| 1992-12-09 | 1994-03-25 | Somalia intervention | 25,000 | 471 days | Shows how a supposedly limited mission can persist well beyond the initial humanitarian or coercive phase. | Office of the Historian: Somalia, 1992-1993 |
| 1965-04-28 | 1966-09-21 | Dominican Republic intervention | 22,000 | 511 days | Another case where an initially bounded intervention turned into a much longer on-the-ground presence. | Office of the Historian: Intervention in the Dominican Republic, 1965 |
| 1950-06-25 | 1953-07-27 | Korean War | 326,000 | 1128 days | Large-country high-force war; important upper-tail anchor for how long a major Asian ground war can last. | National Archives: Korean Armistice Agreement |
| 1965-03-08 | 1973-03-29 | Vietnam War main U.S. ground combat phase | 543,000 | 2943 days | Largest sustained U.S. ground commitment in a hostile country; upper-tail case for long, politically costly entanglement. | National Archives: Paris Peace Accords |
| 2003-03-20 | 2011-12-18 | Iraq War ground commitment | 148,000 | 3196 days | Classic regime-change and occupation analogue: once the United States commits to a major ground campaign, exit can take years rather than months. | Britannica: Iraq War |
| 2001-11-25 | 2021-08-30 | Afghanistan War U.S. ground commitment | 100,000 | 7214 days | Longest modern U.S. ground-war analogue; keeps the far-right tail realistic. | Britannica: Afghanistan War |
Operational Interpretation
The curve is deliberately not a simple 'short war' forecast. The limited-duration layer keeps real mass on a fast-end outcome such as a Kharg-style seizure, a narrow strait operation, or another politically constrained coercive landing that ends in weeks or a few months. But the major-campaign layer preserves the opposite lesson of U.S. history: once a large ground deployment is politically and militarily committed, getting back out can take much longer than decision-makers expect.
Generation Script
The Python script used to produce this template is available for download: generate_market.py