Putin is taking his hybrid warfare to the sea

As a retired admiral and former supreme allied commander of the North Atlantic Treaty Organization, I was thrilled when Sweden and Finland joined the alliance. My first thought was about the vast coastline the two Nordic states provided, essentially turning the Baltic Sea into a "NATO lake."

Russia has a sliver of land on the eastern corner of the sea where Saint Petersburg sits, and another slice with its Kaliningrad territory, located between Lithuania and Poland. But nearly all the Baltic coast is firmly in the hands of the alliance.

This is significant for several reasons. First it is the only interior sea fully within NATO territory: All the other maritime venues for allied forces — the Mediterranean Sea, the Atlantic and Arctic Oceans — are borderlands. Control of the Baltic gives NATO the ability to bottle up the Russian Baltic fleet; vital sea and communications lanes between seven key northern allies; and lots of maritime infrastructure, from huge liquified natural gas terminals and offshore oil and gas facilities, to fiber optic cables on the sea floor.

Russian leader Vladimir Putin intends to contest the Baltic, make no mistake. His Baltic Sea fleet is the oldest Russian naval flotilla, dating back to the early 1700s when it was established under Czar Peter the Great. It is headquartered in the Kaliningrad (which made sense when the three Baltic States — Estonia, Latvia and Lithuania — were part of Russia and later the Soviet Union). Today, it hosts a few surface combatants (destroyers and frigates), a handful of diesel submarines of questionable effectiveness, and a dozen missile-armed patrol craft. Hardly a significant naval force.

However, the Russian Navy often brings in powerful vessels from the Arctic-based Northern Fleet to stage joint exercises. But even with such reinforcements, the conventional Russian naval forces are vastly outgunned — and NATO air forces could likely destroy the Kaliningrad base in the initial hours of a live conflict.

So given that the Russian navy is seriously outclassed by NATO maritime forces, what might Putin do to gain leverage in the Baltic Sea?

As he has in other places around the periphery of the Russian Federation — when he is either outmatched or wants to maintain a level of plausible deniability — Putin will turn to hybrid warfare. This is the potent mix of unconventional combat tactics, techniques and procedures he used to invade Georgia in 2008 and Ukraine in 2014; to meddle with recent elections in Moldova; and to put pressure on the Baltic states.

On land, hybrid warfare can consist of a witch's brew of unmarked combatants in fatigues or even civilian clothes (the so-called little green men); propaganda campaigns and manipulation of social media to sow seeds of dissent and internal confusion; the planting of explosives including car bombs and industrial sabotage; assassinations of civilian and military leaders; and unmarked drones to harass civilian air traffic.

Now Putin is turning to hybrid warfare at sea. This has taken several forms not just in the Baltic but also in the Black Sea, to threaten Ukraine. It involves adapting the land versions of hybrid war to the salt-water environment and adding new twists. Of note, Russia has been using civilian merchant ships to collect intelligence (a sort of modern version of the UK's Q-Ships in World War I); to harass legitimate cargo and tanker traffic; to damage and destroy vital undersea internet and other communication cables; to stage drones for launch against civilian targets ashore; and to hold at risk the sea lanes of communication.

Putin's forces are no doubt developing plans for even more aggressive activities involving supposedly civilian ships. Such vessels could embark Russian Marines (probably in unmarked uniforms) who could assault civilian shipping; carry disguised surface-to-surface missiles that could hit NATO targets ashore; release drone swarms from deep cargo holds; conduct electronic jamming; and disable aids to navigation such as buoys, channel lights, and radio communications between merchant ships, tugs and pilots.

Earlier this year, Norwegian police seized (and then released) a Russian-crewed vessel suspected of sabotage. It was a start, but temporarily holding ships will hardly deter Russia. Rather, NATO should stand up a maritime task force with capabilities, personnel and warships designed to counter hybrid warfare in the Baltic. The alliance's new Operation Baltic Sentry, a standing force including frigates, patrol aircraft, drones and other assets largely for protecting seabed infrastructure, is a good beginning, but not enough.

Russia's gray-zone activities complement the operations of its "shadow fleet" of tankers, which illegally transport hydrocarbons (largely to Asia) to avoid the severe sanctions placed on Moscow. Recently, Finnish special forces seized a Russian shadow tanker and investigated whether it had been involved in cutting undersea cables. Such cases are hard to prove in court, however, given the opaque nature of the Russian merchant fleet.

NATO needs to redouble its maritime patrols by including allies from outside the Baltic — French, Italian, Spanish, American and Canadian naval and coast guard forces — for surveillance and seizure roles. The alliance should also increase its training with an eye toward degrading or destroying the Kaliningrad facilities should direct hostilities break out.

But the most urgent goal is meeting the hybrid threat with commensurate and proportional forces, mostly directed against the shadow fleet. This means identifying ships engaged in possible illegal operations, shadowing them relentlessly within NATO waters, and using maritime special forces (U.S. Navy SEALS, British Special Boat Service, and their equivalents) on clandestine missions to "tag" such vessels with trackers.

NATO should gather ironclad evidence of malevolent actions by Russian ships claiming civilian status; impound them for thorough searches; prosecute crew members proven to be involved in hostile activity; and even destroy ships where the evidence of illegal action is clear. That would send Putin a message about the price of undertaking hybrid warfare.

As always in dealing with Moscow, the key is simple: Respond with judicious but serious levels of force. We need to show Putin that the cloak of hybrid maritime warfare will not hide his illegal and hostile maritime forces in the heart of Europe.

(COMMENT, BELOW)

Stavridis is a Bloomberg columnist. He is a retired U.S. Navy admiral and former supreme allied commander of NATO, and dean emeritus of the Fletcher School of Law and Diplomacy at Tufts University. He is also an operating executive consultant at the Carlyle Group and chairs the board of counselors at McLarty Associates.

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