Traders assign a 96.4% implied probability to No because no European country has concluded a formal bilateral mutual defense treaty with Ukraine that meets the market’s binding criteria. Recent strategic partnership declarations, including Germany’s April 2026 agreement and Bulgaria’s March cooperation pact, have centered on military aid, training, and capacity building rather than creating obligations to defend Ukraine against future aggression. Multilateral efforts through the Coalition of the Willing and the EU’s €90 billion support package have advanced assistance without crossing into individual country commitments. Domestic political constraints in several capitals and the conditioning of deeper guarantees on progress in U.S.-facilitated peace talks further limit prospects ahead of the Ukraine Recovery Conference at the end of June. A last-minute bilateral treaty or sudden shift in a major European government’s position remains the only realistic path that could alter the current consensus.