NATO’s Article 5 collective-defense clause has been invoked only once in history, after the 2001 attacks on the United States, and requires unanimous consensus that an armed attack has occurred. As of August 2026, the ongoing Russia-Ukraine conflict has produced incidents near alliance territory, including drone activity affecting Romania, yet none have met the threshold for invocation. The July 2026 Ankara Summit reaffirmed the alliance’s deterrence posture and sustained military assistance to Ukraine without committing NATO forces directly. Ongoing nuclear signaling by Russia and hybrid threats remain below the level that would trigger formal Article 5 consultations. With roughly five months remaining before 2027 and no verified armed attack on a member state, traders assign a 93.5% probability that the clause will not be activated in the resolution window.