NATO is deploying eyes in the sky and on the Baltic Sea to protect cables and pipelines that stitch together the nine countries with shores on Baltic 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.

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.

Sweden is investigating damage to a data cable linked to Latvia, the latest breach in the Baltic Sea region where European authorities are on high alert.

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.

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.

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.

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.

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.

In addition to the patrols, Defence Minister Hanno Pevkur said countries are weighing other measures to protect cables, including installing sensors to detect anchors dragged across the sea floor or constructing casings or walls around the cables.

Denmark will scrap plans to build new patrol and environmental vessels for the Baltic Sea and instead design ships to carry out tasks around Greenland.