This article assesses the credibility of the current Euro-Atlantic nuclear deterrence in the context of 21st century geopolitical and technological challenges. Russia’s ‘escalate to de-escalate’ strategy and modernisation of its nuclear triad pose significant challenges to NATO’s deterrent credibility. Simultaneously, China’s rapid military advancements and growing strategic alliance with Russia complicate the Euro-Atlantic security picture. The advent of disruptive technologies, such as hypersonic missiles and artificial intelligence (AI), creates new vulnerabilities in nuclear command, control, and communication (NC3) systems, increasing worries about decision-making processes and the possibility of catastrophic mistakes. To meet these developing threats, this paper contends that NATO must modernise its nuclear arsenal, strengthen transatlantic coordination, and pursue strong arms control and diplomatic measures. NATO can adapt to the difficulties of great power rivalry by combining conventional, nuclear, and hybrid response techniques, ensuring its sustained position in global security and stability.