Traders assign a 95.5% probability against Ukraine joining NATO before 2027 because alliance membership requires unanimous ratification by all 32 current members along with completion of a Membership Action Plan that demands extensive military interoperability, democratic reforms, and resolution of territorial disputes. The active conflict with Russia remains the dominant barrier, as NATO statements have repeatedly conditioned progress on an end to hostilities and verifiable security guarantees. Bilateral defense pacts signed with individual allies have not advanced formal accession talks or triggered the consensus vote needed for invitation. Historical cases of post-conflict NATO enlargement show timelines stretching well beyond two years even after fighting stops. A sudden comprehensive ceasefire paired with rapid reform milestones could still shift probabilities, though such alignment faces substantial procedural and geopolitical hurdles within the remaining window.