Russian nuclear-powered submarine Orel was left dead in the water off the coast of the Danish island of Sehero, the Danish Navy said, the Military Observer (Voenniy Obozrevatel) Telegram channel said.
The incident occurred on August 3 as the missile cruiser was returning from St. Petersburg after the completion of the naval parade on the day of the Navy.
The Altai tug boat started preparations for tugging the submarine to the base, but the crew managed to bring the propulsion systems of the submarine back to work.
According to the Danish Navy, the anti-submarine ship Vice-Admiral Kulakov interacted with the Coast Guard of Denmark during the incident.