5% — Will US withdraw from NATO by...
Polymarket 5% · 1 contracts · $849 volume · low confidence
Updated 2026-06-19 15:34:38 UTC

Why this matters:
This market estimates a 10% chance the United States withdraws from NATO by a specified deadline. NATO membership is formalized through treaty, requiring congressional action and formal notification to withdraw. The probability reflects the low baseline likelihood of such a major institutional shift, though it acknowledges the possibility of significant political changes. Factors that could increase this probability include further deterioration of US-European relations, shifts in burden-sharing disputes, or major changes in US foreign policy leadership. Factors that could decrease it include strengthening of NATO during potential security crises or demonstrated allied commitment to mutual defense obligations. Key upcoming events include NATO summit meetings, European defense spending announcements, and any statements from US leadership regarding alliance commitments. The current low probability suggests markets view institutional continuity and alliance structures as relatively stable despite periodic political tensions.

Key factors:
- NATO withdrawal requires formal US government action including congressional authorization and treaty notification, creating multiple institutional checkpoints
- Current US leadership statements and recent policy direction toward NATO will be observable indicators of withdrawal likelihood
- Any NATO Article 5 invocation or major security crisis involving member states would likely reduce withdrawal probability sharply
- European defense spending increases and burden-sharing agreements could influence US commitment levels and political willingness to withdraw
- Scheduled NATO summits and defense ministerial meetings in 2026 will provide concrete data on alliance cohesion and US engagement level

Contracts:
- Will US withdraw from NATO by...?: December 31 — 5¢ Polymarket $849 (weight 100%)

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## Methodology

SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours.

## SF Signal

- SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration.
- No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only.

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*Last verified: 2026-06-19T01:20:20.801Z*

By SimpleFunctions — https://simplefunctions.dev/

Cite as: "5% per prediction markets (SimpleFunctions, June 2026)"
Canonical: https://simplefunctions.dev/answer/us-withdraw-from-nato
Full data: https://simplefunctions.dev/api/public/query?q=Will%20US%20withdraw%20from%20NATO%20by...
Provider: SimpleFunctions — https://simplefunctions.dev