NATO is ratcheting up its guard against suspected attempts to sabotage underwater energy and data cables and pipelines that crisscross the Baltic Sea.

Crew on board an oil tanker accused of sabotaging undersea power and communications cables in the Baltic Sea were poised to cut other cables and pipelines when Finnish authorities boarded the vessel last month,

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.

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.

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.

Sweden detained a vessel suspected of damaging a subsea data cable connecting it with Latvia, the third such incident in the Baltic Sea in the past three months.