Nato countries have stepped up patrols to protect critical underwater infrastructure in the Baltic Sea, which is bordered by eight countries, and other waters. A Royal Navy submarine was ordered to surface last November close to a suspected Russian spy ship which was loitering over undersea infrastructure in UK waters.

Shipping firms may need to pay a fee to use the Baltic Sea, one of the world's busiest shipping routes, in order to cover the high costs of protecting undersea cables, Estonia's defence minister said on Wednesday following a spate of breaches.

With its powerful camera, the French Navy surveillance plane scouring the Baltic Sea zoomed in on a cargo ship plowing the waters below — closer, closer and closer still until the camera operator could make out details on the vessel's front deck and smoke pouring from its chimney.

After a series of suspected undersea cable cuttings, NATO has launched a new surveillance and deterrence mission to protect critical infrastructure under the Baltic Sea.

An undersea data cable between Latvia and Sweden was damaged early on January 26, the latest in a series of similar incidents in the Baltic Sea in which critical seabed energy and communications lines are believed to have been severed by ships traveling to or from Russian ports.

The RAF is providing RC-135 Rivet Joint and P-8 Poseidon MRA1 aircraft from the Intelligence, Surveillance, Target Acquisition and Reconnaissance (ISTAR)

Sweden has opened a preliminary investigation into suspected aggravated “sabotage” and ordered the detention of a vessel in the Baltic Sea suspected of damaging an underwater fiber optic cable connecting Latvia and the Swedish island of Gotland earlier that day.

Estonia's defence minister on Wednesday said ships may have to pay a fee to use the Baltic Sea to cover costs of protecting undersea cables.

Russia has condemned the Western alliance for ramping up its naval presence in the so-called 'NATO lake' after alleged sabotage by Moscow-linked vessels.

The Nordic country has opened an investigation into the damage, just weeks after NATO stepped up its military presence in the area following a series of similar incidents.

STOCKHOLM (Reuters) - Swedish authorities boarded a Maltese-flagged ship seized in connection with the latest breach of cables running along the bottom of the Baltic Sea to begin an investigation into the matter, the country's security police said on Monday.

A Bulgarian shipping company on Monday denied that one of its ships had intentionally damaged an underwater fiber optic cable connecting Latvia and the Swedish island of Gotland.