NATO’s Article 5 collective-defense clause remains uninvoked since its sole use after the 2001 attacks, reflecting sustained deterrence and the absence of qualifying armed attacks on member territory. Recent Russian drone incursions into Poland and airspace violations over Estonia prompted only Article 4 consultations and enhanced eastern-flank measures such as Operation Eastern Sentry, while the ongoing Russia-Ukraine conflict has not crossed into NATO borders. Allies have accelerated defense spending above 2 percent targets, conducted large-scale exercises, and integrated new members to reinforce credibility ahead of any potential threshold. Uncertainties around U.S. commitments under the current administration have surfaced in debates over Greenland and burden-sharing, yet these have not altered the pattern of calibrated responses short of invocation. Traders price the low likelihood of escalation to Article 5 before 2027 on this track record of de-escalation and institutional preparedness.