NATO's collective defense clause under Article 5 has been invoked only once in its history, following the 2001 attacks on the United States, and remains untriggered amid the ongoing Russia-Ukraine conflict. As of September 2026, recent Russian drone strikes near the Poland-Ukraine border and hybrid incidents such as airspace violations and sabotage attempts have prompted NATO consultations under Article 4 and EU discussions of parallel mechanisms, yet allies have responded with measured support for Ukraine and defensive enhancements rather than direct intervention. NATO Secretary General Mark Rutte and member states have emphasized bolstering eastern flank defenses and long-term assistance pledges without crossing into armed collective action. With limited time remaining before 2027 and no verified state-on-state armed attack on alliance territory, trader consensus reflects the low near-term likelihood of the threshold being met.