A NATO sub hunter captured these shots of a Russian submarine in waters newly surrounded by the alliance

• A NATO ally captured images of a Russian submarine in the Baltic Sea last week.
• The submarine was spotted by a Portuguese P-3 Orion maritime patrol aircraft.
• Russia conducted sub drills, including a torpedo duel, in the Baltic Sea recently.

A NATO ally's anti-submarine warfare aircraft captured photos of a Russian sub navigating the Baltic Sea last week, highlighting the alliance's continuous efforts to keep track of Russian activity in the undersea domain.

The surveillance photographs, which show the surfaced submarine, were taken around the same time the Russian military conducted submarine exercises in the Baltic Sea, which involved a pair of subs engaging in a torpedo duel.

NATO Maritime Command shared the photos on X and other social media platforms on Wednesday, noting that the Russian sub was photographed by a Portuguese P-3 Orion maritime patrol aircraft, an ASW platform made by Lockheed Martin.

The P-3 Orion anti-submarine and maritime surveillance aircraft was used by the US Navy for decades until it was succeeded by the sophisticated P-8A Poseidon, an advanced aircraft introduced in 2013 and highly regarded as one of the best maritime patrol aircraft in service. Other nations continue to use the P-3s, though.

A P-8 Poseidon recently operated over the Norwegian Sea late last month, joined by a US Navy nuclear ballistic missile submarine and other vessels and aircraft, including an E6-B Mercury "Doomsday" plane, in what appeared to be an unusual flex amid persistent tensions with Russia.

While it's unclear what Russian sub was documented in these photos, Russia recently conducted a submarine exercise in the Baltic Sea. Two Russian Kilo-class, diesel-electric subs — the Novorossiysk and Dmitrov — held a training duel involving torpedo fire last week, around the same time the NATO photos were taken.

After wrapping up the duel, the Russian submarines — capable undersea assets known for being relatively quiet, especially the more advanced Novorossiysk — went on to conduct other combat exercises in the Baltic Sea, Russian state media said.

The Baltic Sea, where the drills took place, has seen a major geopolitical shift in recent years with Russia's invasion of Ukraine and Finland and Sweden both joining NATO. Sweden became the newest member in March 2024.

With eight of the nine countries bordering the Baltic Sea now being NATO members — the only remaining one Russia — the body of water is sometimes called a "NATO lake," although this term has been criticized for glossing over how strategically important the region is for both NATO allies and Russia alike.

Russian submarines are active far beyond the Baltic Sea and remain an important element of the Russian navy. For instance, the submarine Kazan was spotted in Cuba recently during a Russian navy flotilla visit and prior to exercises in the Caribbean. The Kazan is one of a class of Russian submarines that have concerned NATO allies for years.