The Finnish Navy dropped depth charges on an unidentified suspected submarine near Helsinki, the Finnish Navy announced on Tuesday, April 28, 2015. Photo Courtesy Finnish Navy.

HELSINKI, Finland, April 28 (UPI) -- Depth charges were dropped on an underwater presence believed to be a foreign submarine, the Finnish Navy announced Tuesday.

The unidentified object was located Monday in Finnish territorial waters off the city of Helsinki, and was located again Tuesday, when the charges, similar to hand grenades, were launched into the water as a warning.


"The bombs are not intended to damage the target; the purpose is to let the target know that it has been noticed," Commodore Olavi Jantunen told the Helsinki News.

Defense Minister Carl Haglund noted the object could have been a submarine spotted in the Baltic Sea earlier this week.

"We strongly suspect that there has been underwater activity that does not belong there. Of course it is always serious if our territorial waters have been violated," Haglund told Finnish news agency STT, adding the unidentified object has likely left the area but an investigation will continue.

It was not resolved if the subject of the hunt near Helsinki was a submarine.

Finland has observed an increase in military exercises by Russia, with which it shares an 800-mile border. In October the Finnish military activated troops, helicopters and ships to a search of the Stockholm archipelago for a suspected Russian submarine, which, it was later learned, was a Swedish civilian boat.