Strategic Submarines and Nuclear Diplomacy: The Silent Deterrence Resurging in 2025

Amid an increasingly tense international landscape, marked by geopolitical rivalries and mutual distrust among powers, the deployment of strategic submarines with nuclear capability has once again taken center stage in global security dynamics. This resurgence, reminiscent of the toughest periods of the Cold War, has become a key element in modern nuclear diplomacy, where deterrence remains a fundamental tool—albeit now under new rules and with a more diverse set of actors.

In the Pacific Ocean, the United States has intensified its presence through the deployment of the USS Kentucky, an Ohio-class submarine equipped with Trident II nuclear ballistic missiles. This action is no coincidence. Washington seeks to send a direct message to Beijing in response to China’s growing military development and recent hypersonic missile tests. China, for its part, has strengthened its fleet of nuclear submarines, particularly the 094A-class, armed with JL-3 missiles capable of reaching U.S. territory from waters near its coast.

The increasingly active presence of these submarines in the South China Sea indicates that the Asian giant is unwilling to yield in the struggle for strategic balance in the region.

Meanwhile, Russia has resumed strategic patrols in the Arctic with Borei-A-class submarines, such as the Knyaz Vladimir, recently detected near the Svalbard archipelago. Moscow claims these are routine maneuvers, but for NATO, this activity is a reminder of Russia’s renewed interest in militarizing the Arctic, an area of growing geostrategic value due to ice melt and the opening of new maritime routes.

In this context, nuclear diplomacy is trying to adapt to an increasingly complex environment.

The recent Strategic Security Summit in Vienna, which brought together representatives from the United States, China, Russia, France, and the United Kingdom, made it clear that there are intentions to avoid a new submarine arms race. Proposals discussed included joint verification mechanisms, transparency protocols, and the creation of demilitarized zones for strategic submarines. However, concrete progress was limited, and the differences between powers remain deep.

What is emerging in 2025 is a new type of global equilibrium, where nuclear deterrence is not expressed through parades or public declarations, but through silent submarine patrols thousands of kilometers beneath the surface. The inherent opacity of these deployments increases the risk of misunderstandings or accidents, making stronger multilateral agreements adapted to 21st-century challenges urgently necessary. Beneath the waves, the Cold War never fully ended; it simply became quieter and harder to track.