Brussels:

Sweden’s membership of NATO adds the final piece of the puzzle to the alliance along the strategically important Baltic Sea coast, but Russia remains a threat both above and below the surface.

After Finland joined Sweden last year, Sweden’s accession – which looks set to clear the final hurdle as Hungary votes to ratify later on Monday – means all countries around the Baltic Sea except Russia will join U.S.-led forces part of the alliance.

This has led some to refer to the stretch of sea as a “NATO lake”, with Western allies now appearing to be well-positioned to choke off Russia’s room for maneuver on this crucial shipping lane should war break out with Moscow.

But analysts warn that while Sweden’s membership makes it easier for NATO to exert control and strengthen its fragile Baltic states, Russia can still threaten the region from its heavily armed enclave of Kaliningrad and threaten undersea infrastructure.

“If you look at the map, geographically the Baltic Sea is becoming a NATO lake, yes,” said Minna Alander, a researcher at the Finnish Institute of International Affairs.

“But NATO still has work to do.”

Since Russia invaded Ukraine, a series of high-profile incidents involving undersea pipelines and cables in the Baltic Sea have served as a wake-up call for NATO about its vulnerabilities.

In September 2022, the Nord Stream gas pipeline between Russia and Europe was hit by sabotage attacks. More than a year later, investigators still have not released the name of the person responsible.

Last October, a natural gas pipeline and cable from Finland and Sweden to Estonia were damaged. Finnish police said they believed a Chinese cargo ship may be involved.

In response, NATO has stepped up naval deployments and sought to bolster its surveillance capabilities, but keeping an eye on what’s happening underwater is a major undertaking.

“It would be very difficult to fully control the oceans in the same way that we control land territory,” said Julian Parack, a researcher at the Bundeswehr University in Hamburg, Germany.

“The damage at Nord Stream shows, among other things, that we still have a hard time understanding exactly what is happening below the surface and on the seafloor.”

– Kaliningrad threat –

Sweden has long had a close partnership with NATO, but its full membership will allow it to be fully integrated into the alliance’s defense plans.

In addition to its long Baltic coastline, Sweden also owns the island of Gotland, which will play a central role in helping NATO enforce its will.

But across the water, Russia has its important outpost, the exclave of Kaliningrad.

Moscow, sandwiched between Poland and Lithuania, has turned the region into one of Europe’s most militarized in recent years, deploying nuclear-capable missiles there.

Russia’s Baltic Fleet in Kaliningrad is a shadow of its Cold War days, and the invasion of Ukraine has weakened some of Russia’s forces in the region.

But John Deney, a research professor at the U.S. Army War College, said the Kremlin has maintained investments in undersea capabilities and still has the firepower to conduct small landings or threaten NATO supply lines.

“In terms of artillery, indirect fire and nuclear weapons, their firepower and range exceed that of their NATO allies in the region,” Deni told AFP.

“Allies must confront this threat and push back.”

On the other hand, although Stockholm has a rich naval heritage, like other NATO countries in the region, its maritime power in the Baltic Sea is still insufficient.

“NATO naval assets are relatively limited even when you include Sweden,” Deni said, adding that allies needed to develop the ability to clear mines under fire.

– Strengthening the Baltic States –

The three countries relieved to have Sweden and Finland join are the NATO Baltic states of Estonia, Latvia and Lithuania, long seen as the alliance’s Achilles’ heel.

War planners have been grappling with how to prevent Russian armies from being cut off if they capture the 65-kilometer (40-mile) Suwalki gap between Belarus and Kaliningrad.

Sweden’s location astride the North and Baltic Seas creates a critical route for transporting additional NATO troops to provide protection in the event of an attack.

“It enables the U.S. military to promptly reinforce the Baltic states, especially the frontline states,” said Tuli Dunidun, Estonia’s deputy minister for defense policy.

However, although NATO is happy about Sweden’s joining, American scholar Denis insists that the alliance should be suspended considering that the Baltic Sea is its own property.

“Calling them ‘NATO lakes’ breeds complacency,” Deni said.

“The challenge and threat posed by Russia in the region are significant in some respects, and allies currently lack the capacity to meet this challenge in a crisis.”

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)