By Essi Lehto and Tom Little
GULF OF FINLAND, Sept 17 (Reuters) - Finnish authorities boarded and searched a target vessel in the Baltic Sea on Thursday in a live drill that officials said shows how seriously the region takes the threat of undersea sabotage after a string of incidents.
Finland and the wider Baltic Sea region have experienced ruptures of power cables, telecom lines and gas pipelines following Russia's invasion of Ukraine in 2022, raising concerns that critical infrastructure lacks sufficient protection.
Masked officers from the coast guard, police and armed forces on Thursday fast-roped onto a vessel's deck from a helicopter, securing the crew and sweeping the ship room by room.
Coast Guard Commander Ilja Iljin, who led the drill, said the exercise reflects what Helsinki considers "the new normal".
"In the past two or three years we've had several incidents in the Baltic related to the damaging of critical underwater infrastructure," Iljin said. "So we have to be ready for when the next event happens."
Signs that a ship may be involved in cable damage include abrupt changes in speed or course as it passes over an undersea line, Iljin said.
Finland's response has sharpened with each incident. The first suspect ship sailed on before authorities could act, while the most recent was under control within hours.
In a real call-out, police officers on standby can be at their base within an hour, before deploying by helicopter or boat, said Chief Inspector Juha Hietala of the police's special intervention unit.
While most incidents were caused by vessels dragging their anchors, officials are also preparing for sabotage by divers, mini-submarines or diving robots carrying explosives.
The government is separately seeking new powers to let the Border Guard authority, including the coast guard, stop and inspect ships suspected of being stateless or falsely flagged, and to intervene against unmanned underwater vehicles.
(Reporting by Tom Little and Essi Lehto, Editing by Terje Solsvik and Timothy Heritage)
