Russian Borei-Class Ballistic Missile Submarine Transits La Perouse Strait for First Time

Unprecedented Submarine Transit Near Japan

A Russian Navy Borei-class ballistic missile submarine was observed transiting the La Perouse Strait on Wednesday, September 24, 2025, marking the first time such a vessel has been detected in the area by Japanese officials. The submarine, a nuclear-powered vessel equipped with ballistic missiles, was spotted around 5 p.m. local time, sailing westward through the strait.

The Russian submarine was accompanied by the cruiser RFS Varyag (011), which serves as the flagship of the Russian Pacific Fleet, and the rescue tug Fotiy Krylov. The vessels were sighted approximately 24 miles northeast of Hokkaido's Cape Soya.

Monitoring and Strategic Significance

Japan's Maritime Self-Defense Force (JMSDF) actively monitored the Russian naval group. The monitoring efforts included the deployment of the fast attack craft JS Watakata (PG-825) and a P-3C Orion Maritime Patrol Aircraft. The transit is considered significant as it represents the first recorded sighting by the JMSDF of a Borei-class ballistic missile-equipped nuclear-powered submarine operating near Japan.

The La Perouse Strait, also known as the Soya Strait, is a crucial international waterway. It separates Japan's northern island of Hokkaido from Russia's Sakhalin Island and connects the Sea of Japan to the Sea of Okhotsk. Japan's territorial waters in this strait extend only three nautical miles, rather than the conventional twelve, a measure reportedly in place to permit nuclear-armed United States Navy vessels to transit without violating Japan's non-nuclear principles.

Context of Regional Naval Activity

The presence of the Russian submarine follows a period of increased naval activity in the region. Just days prior, a People's Liberation Army Navy (PLAN) surface action group also transited the La Perouse Strait on Monday and Tuesday. Furthermore, there have been recent sightings of both Russian and Chinese surveillance ships operating near Japan.

Russia's fleet includes eight Borei-class submarines, with five of these assigned to its Pacific Fleet. These submarines are designed to bolster Russia's nuclear deterrence capabilities, replacing older Soviet-era classes.