ABOARD FRENCH MARITIME PATROL AIRCRAFT ATL 2 — Above the Baltic Sea, about four hours after taking off from Brittany’s Lann-Bihoué airbase, the crew of the French Atlantique ATL2 aircraft found what they were looking for, cutting through the light-blue water: a Russian warship. 

Inside the narrow, 31-meter-long plane, one of the operators watching multiple screens was adamant: “That’s not from NATO,” he said, as he keyed the vessel’s features into a classified database. 

The ship was indeed a Russian military vessel — a Neustrashimy class frigate — returning from the Mediterranean Sea. The French military officers aboard the Nov. 14 flight had been expecting it, as NATO allies patrolling the area a day earlier had warned it was on the way.

The encounter is an increasingly regular occurrence over the Baltic Sea, which has seen intensified NATO patrols following Russia’s 2022 full-scale invasion of Ukraine.

The area has become “a critical zone of direct contact with the Russian Federation in the air, at sea, underwater and in cyberspace. A zone of contact, then a zone of potentially destabilizing friction,” said Cyrille Bret, an associate researcher at the Institut Jacques Delors Notre Europe think tank, who recently published a paper on the importance of the Baltic Sea for Europe’s security.  

The Baltic is crucial to both NATO and Russia.

Following Sweden and Finland’s joining the alliance, it is largely — but not quite — a NATO lake and a key route to transport goods and hydrocarbons, as well as the location of infrastructure such as subsea telecoms cables.

For Russia, meanwhile, the Baltic provides access from the outside world to St. Petersburg — itself a hub for oil and gas shipments carried by the shadow fleet the Kremlin uses to skirt Western sanctions. It also allows navy vessels to sail into the North Atlantic from Russia proper and from the heavily militarized exclave of Kaliningrad.

During the mission, the goal of the French navy ATL2 “is to be visible without being aggressive or escalatory,” said Lieutenant Marc, the aircraft’s commanding officer, as the plane lifted off from France. (French officers can’t disclose their surnames for security reasons.)

“Our mission is to fly over the Baltic Sea to show that we’re there, to reassure neighboring countries, but also to find out what’s going on and gather intelligence,” he added. “The Baltic Sea is not a Russian preserve, it’s a NATO sea.” 

Maritime patrols are part of a wider NATO deterrence posture that includes naval exercises such as Finland’s Freezing Winds, which this year focused on amphibious warfare and protecting critical infrastructure.

With the growing importance of the Baltic and an increase in incidents involving undersea cables and pipelines, NATO is reportedly considering having surveillance drones patrol the waterway permanently.

“Russia is waging a form of covert warfare (a “hybrid war”) in the region against the countries bordering the Baltic Sea, all of which are now designated as enemies,” wrote Jean-Sylvestre Mongrenier, director of research at the Thomas More Institute, a foreign policy think tank based in Paris and Brussels. Russia has been accused of cyberattacks and of sabotaging critical infrastructure and jamming GPS signals.

Russian habits

The frigate wasn’t the only Russian ship spotted by the French aircraft. Flying below the heavy clouds, the crew also saw a civilian freighter that features on NATO’s watch list, which they said was likely carrying weapons.

“Finding out about [the Russians’] habits is a task that requires time and patience,” said Sub Lieutenant Joël, the aircraft’s tactical coordinator. “Analysts will be able to tell if the [ships are] loaded and, if so, with what,” he added, referring to the Russian civilian vessel.

The twin turboprop ATL2 — produced by Dassault Aviation for the French navy in the 1980s — was designed for anti-submarine and anti-surface warfare and can carry torpedoes and Exocet anti-ship missiles. It’s also equipped with a scanned array radar with a 400-kilometer range, digital acoustic processing systems, and combat mission software.

The information gathered by the 19-member crew — 18 men and one woman — is sent back to both NATO and France.

The alliance wants to keep an eye on maritime traffic, on what the Russian air force is up to, and also on Kaliningrad. The Russian exclave’s naval and air bases, located between Poland and Lithuania, host cruise missiles, surface-to-air-missile batteries and, according to Polish Foreign Minister Radosław Sikorski, up to 100 nuclear weapons. Military radar trackers often show NATO aircraft circling near the exclave to gather intelligence.

France started patrolling the Baltic Sea  in 2021, the year before the Ukraine war started. According to an analysis of France’s pivot to Europe’s eastern flank by the Paris-based IFRI think tank, “France has taken note of the resurgence of security challenges in the Baltic and is increasing its presence in the area.”

French aircraft overfly the Baltic roughly every month.

In the past few years “we’ve refined our knowledge of the area,” said a high-ranking French military officer, speaking on condition of anonymity.

In contact with Russia 

The Baltic Sea encounters were part of a series of interactions between NATO and an increasingly aggressive Russia. In recent weeks, a Russian aircraft violated Estonia’s airspace, while two Dutch F-35 fighters intercepted three Russian aircraft over the Baltic. Last year, NATO air forces across Europe scrambled well over 300 times to intercept Russian military aircraft approaching alliance airspace, NATO said.

In early December, a Russian navy ship fired a signal flare toward a German military helicopter over the Baltic.

During the almost 11-hour flight, some 30 minutes were spent in international airspace that is monitored by Russian air-traffic control. Crew members said the goal is not to behave in an “escalatory way;” NATO has defined the maximum distance that can separate allied aircraft from Russian coasts and ships.

The interactions between NATO allies and Moscow are carefully choreographed. One of the main challenges is not to misinterpret what the other side is doing, in order to avoid a diplomatic incident — or worse.

On the day of the French mission, the Russians declared a firing practice zone that had to be avoided around Kaliningrad. It’s a routine procedure designed to make maritime patrols more difficult and to “mess with NATO,” the senior French military officer said.

When nearing Kaliningrad, the ATL2 informed Russian air traffic control of the aircraft’s intentions and route. After a few minutes, the Russian controller called back.

“I suggest you turn left,” he said in English, implying that it was now time for the French plane to leave.

The dialogue was polite throughout, a French military officer stressed after the flight. But the interaction also demonstrated that “the Russians are paying attention.”