Swedish naval ships, helicopters and ground troops combed waters near Stockholm Monday after credible reports of foreign undersea activity and a suspected Russian intrusion sparked a submarine hunt not seen since the Cold War era, reports GHN based on Fox News.
The Russian Defense Ministry denied there were any emergency situations involving Russian warships Sunday and suggested a Dutch submarine might have triggered Sweden's alert, after carrying out exercises in the area.
The theory, however, was dismissed by the Dutch defense ministry Monday, French news agency AFP reported.
Countries around the Baltic Sea remained on edge as the submarine hunt continued for a fourth day, seeking signs of a foreign submarine or smaller underwater craft that officials suspect entered Swedish waters illegally.
The armed forces published a photograph taken on Sunday by a passerby showing a partially submerged object in the water from a distance, but it was unclear what kind of vessel was in question.
The military said the intelligence operation in the Baltic Sea -- less than 30 miles from Stockholm -- involved a few hundred people.