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.

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.

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.

NATO countries will deploy frigates, patrol aircraft and naval drones in the Baltic Sea to help protect critical infrastructure and reserve the right to take action against ships suspected of posing a security threat,

Sweden on Sunday said it had seized a ship suspected of having damaged a fibre-optic cable under the Baltic Sea linking the country to Latvia, which sent a warship to