NATO’s Article 5 collective-defense clause has remained uninvoked since its sole historical use after 9/11, and mid-2026 trader pricing at 91.5% for no invocation before 2027 reflects the continued absence of any armed attack on alliance territory. The Russia-Ukraine conflict has generated periodic drone and airspace incidents along NATO’s eastern flank, including strikes reaching Romanian territory in May 2026, yet these have prompted only Article 4 consultations and enhanced vigilance rather than a formal Article 5 trigger. Recent alliance summits have prioritized forward deployments, higher defense-spending commitments, and operational planning to reinforce deterrence, while U.S. pressure on European allies to assume greater conventional-defense responsibilities by 2027 has centered on alliance strengthening. These dynamics sustain the market’s assessment that a qualifying armed attack on a member state remains unlikely in the near term absent a major escalation directly targeting NATO territory.