LONDON — Vaindloo island, a tiny rocky outcrop in the Gulf of Finland, is serving as an unlikely barometer for rising tensions between NATO and Russia.

On Sept. 19, three Russian MiG-31 jets entered Estonian — and therefore NATO — airspace over Vaindloo, remaining in the airspace for 12 minutes and traveling nearly 125 miles west.

An Estonian Defense Ministry spokesperson told ABC News that the September MiG-31 intrusion was “unprecedentedly brazen,” but it was far from the first. Italian, Swedish and Finnish fighter jets were all involved in shadowing or intercepting the MiG-31s, the spokesperson said.

Vaindloo — Estonia’s most northernmost point — has an area of just 15 acres, but the uninhabited island sits at a strategic choke point. It is situated in the busy Gulf of Finland, 14 nautical miles from the Estonian mainland and 29 miles south of the Finnish mainland.

Thirteen miles to the northeast is the Russian island of Rodsher. Further east along the maritime corridor are the busy Russian ports of Primorsk and Ust-Luga, before the Gulf of Finland reaches its easternmost edge. 

There sits the Russia Baltic Fleet’s naval base at Kronstadt⁩⁦, and beyond it St. Petersburg — the former imperial capital raised from malarial marshes as Peter the Great’s “window onto Europe.”

It is a window that many in Europe — not least in Ukraine — would like to see closed. 

“Europe has the right to close straits and sea routes to protect itself,” Ukrainian President Volodymyr Zelenskyy said last month after a spate of drone sightings over northern European airports, with officials hinting that the craft may have taken off from Russia-linked tankers transiting the region having departed from Russian ports.

The Gulf of Finland serves as a key air and sea bridge from Russia to the rest of the world, connecting Moscow’s military and commercial fleets to its Baltic Sea exclave Kaliningrad, on to the North Sea and into the Atlantic Ocean. 

For Russian President Vladimir Putin and the Kremlin, the route is a key conduit for the energy exports that are funding the war on Ukraine, including those carried by its so-called “shadow fleet” of tankers allegedly used to evade international sanctions.

“Russia is using this corridor to export 60% of oil and gas from Russia,” Estonian Foreign Minister Margus Tshakna told ABC News. “It’s very intensive. We’re talking about maybe 400 or more vessels per week. It’s a huge thing.”

“If we are talking about Russian aggression, if it started, of course, it will be closed and controlled totally by NATO — our allies and us,” Tsahkna said of the Gulf of Finland and the wider Baltic Sea. For now, though, “Russia has a right to pass,” he said.

Eyes on the sky

Recent Russian airspace violations in the Baltic Sea region — both by manned and unmanned aircraft — have ratcheted up tensions.

Since Moscow launched its full-scale invasion of Ukraine in February 2022, Russian aircraft have violated Estonian airspace eight times, the Defense Ministry spokesperson said. Four such violations have occurred this year, they said.

The latest incident prompted Estonia to trigger NATO’s Article 4, gathering allies for consultations. The alliance later issued a statement warning Russia that it would use “all necessary military and non-military tools” to defend itself, condemning Moscow for a “pattern of increasingly irresponsible behaviour.”

Allies characterized their response as “effective,” but it did little to tone down the rhetoric from Moscow. As NATO officials and leaders discussed the possibility of shooting down intruding Russian manned aircraft, Russia’s Foreign Minister Sergei Lavrov said such a response would constitute an act of war.

NATO said it is bolstering its defenses on its eastern flank, launching the “Eastern Sentry” operation by which allies will deploy more jets and air defense resources to the region, and enhance inter-allied cooperation in responding to aerial threats.

Italy also said it would extend its deployment of a SAMP/T air defense system in Estonia until the spring of 2026, the Estonian Defense Ministry spokesperson said.

“Russia’s goal is to divert attention and assistance away from Ukraine and to force NATO countries to focus more on the defense of their own territories,” they added. “Allies will not be deterred by these and other irresponsible acts by Russia from their enduring commitments to support Ukraine.”

Russian violations have prompted NATO nations to update their rules of engagement, streamlining the process of identifying and shooting down incurring drones. 

Some, like Polish Foreign Minister Radoslaw Sikorski, have said NATO nations should extend their air defense shield into western Ukraine, to both protect territory there and prevent Russian munitions from reaching allied borders. Last month, Sikorski said that “opinion is shifting towards this idea.”

Tsahkna said that idea is still under internal discussion. “Let’s see what the future brings,” he said.

Also now subject to intense debate is whether NATO nations should down manned Russian aircraft violating allied airspace. Estonian officials defended their decision not to fire on the MiG-31s last month, saying their trajectory and weapons loadout showed they posed no threat to life.

“Everything worked perfectly,” Tsahkna said. “There was no immediate military threat to Estonia this time.”

“If there would have been a direct military threat to Estonia, all these protocols and everything are there — NATO could have acted,” the foreign minister added.

U.S. President Donald Trump raised eyebrows when reporters at the United Nations General Assembly asked him if NATO should shoot down intruding Russian aircraft. “Yes, I do,” the president responded. 

Tsahkna said it was “very important that the president of the United States put it very clearly on the table in terms of speaking in the language that Putin understands.”

Pinning down the ‘shadow fleet’

The Baltic Sea could become a key theater in any future conflict between Russia and its Western adversaries. It handles some 15% of global shipping traffic, covering some 145,560 square miles of sea crisscrossed by as many as 4,000 ships per day, according to some estimates.

Russia’s full-scale invasion of Ukraine prompted both Finland and Sweden to jettison decades-long policies of neutrality and join NATO. Some allied officials subsequently took to referring to the Baltic Sea as the “NATO Lake,” a tongue-in-cheek nod to a seismic strategic shift that appeared to greatly limit Russian opportunities in the region.

But NATO’s near-total domination of the Baltic Sea’s 5,000 miles of coastline has not prevented several high-profile acts of alleged undersea sabotage. Natural gas pipelines, power cables and internet cables have all been damaged, with ultimate responsibility still murky and subject to sprawling pan-national investigations.

“We are controlling, NATO is patrolling, NATO presence here is really very strong,” Tsahkna said when asked if the alliance is allowing too much Russian freedom of operation in the Baltic Sea.

European nations have introduced new sanctions on and increased surveillance — and at times, conducted boarding operations and inspections — of suspected shadow fleet vessels, Tsahkna said. European capitals are also reaching out to nations under whose flags these Russia-linked vessels fly, asking them to help the pressure campaign, the minister said.

“The pressure on Russia is increasing heavily,” Tsahkna said, “We have many things to do more.”

European nations are constricted in peacetime, Tsahkna added, but are aware of the danger. 

“We need to control what is happening there, because this opportunity is used wrongly by Russia, which is not following any international cooperation or the agreements or conventions, and it makes the situation more delicate,” he said.

“The shadow fleet topic is more complicated, and we are trying to deal with it — as well the undersea cables and all this infrastructure — to protect them,” Tsahkna continued. “We have heavily increased our capabilities. But, you know, globally, they’re always vulnerable.”

Recent weeks have seen the emergence of a new potential threat — unidentified drones flying over military and critical infrastructure sites all across northern Europe. Their origin and purpose are yet to be conclusively established, but European leaders have linked their appearance to Moscow.

“This is a part of the hybrid actions that have been taking place already for years,” Tsahkna said. “It’s not proven yet who is behind these actions, but I think that Putin is making a very big mistake here. Because NATO transatlantic allies are very much united and investing even more.”