Finnish navy probe doesn't rule out presence of foreign submarine in territorial waters

Finnish military officials say that an "underwater object" the navy chased last month in territorial waters and dropped several depth charges could have been a foreign submarine.

A navy investigation released Thursday says that technical analysis did not provide sufficient proof of the presence of a submarine during the April 27-28 search off the coast of Helsinki with inconclusive sound data, but that the existence of "of a submarine, or underwater activity" could not be ruled out.

The incident followed a lengthy hunt for a foreign submarine in the waters of neighboring Sweden in October during a period of growing military activity in the Baltic Sea region, with several reports of airspace violations by Russian military aircraft and an increased presence of Russian military vessels.