Traders assign an 87% probability against NATO invoking Article 5 before 2027 because no armed attack on alliance territory has occurred since the sole historical precedent after September 2001. The Russia-Ukraine conflict has prompted Article 4 consultations, such as following the 2025 Polish drone incursions, yet remained below the collective-defense threshold through enhanced forward deployments and eastern-flank reinforcements. Allies have accelerated defense spending increases, including commitments toward higher GDP targets, while U.S. statements on burden-sharing have not altered operational deterrence. Absent escalation involving direct strikes on members or new conflicts crossing into NATO airspace or soil, the prevailing diplomatic and military posture supports the market’s assessment of continued non-invocation through the period.