Turkey's recent veto of Israel's participation in a NATO exercise undermines the alliance's defense framework and provides opportunities for Russia and Iran to exploit. Turkey's divergence from NATO's strategic principles, including its purchase of Russia's S-400 missile defense system, compromises alliance cohesion and security. By vetoing Israel's participation, Turkey weakens NATO's operational readiness and compromises the national defense interests of member states. NATO should evolve its consensus principle to prevent single-state obstructionism and deepen strategic partnerships with reliable allies like Israel to strengthen collective defense capabilities. Addressing Turkey's divergence is essential to preserving the alliance's effectiveness.