Amid growing tensions with Russia, the Finnish navy have fired underwater depth charges after the movements of a suspected submarine, off the coast near the capital Helsinki, were identified.
The Finnish navy said it bombed the mysterious object, which it believes as a submarine, after repeated sightings in Finnish territorial waters. The grenade-size charges were dropped as a warning.
The ministry has also dispatched ships to scour the area for any potential target.
"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. The bombs are not intended to damage the target, the purpose is to let the target know that it has been noticed," Defence Minister Carl Haglund told the country's news agency STT.
Haglund did not mention Russia's involvement in the incident but insisted Finland does not frequently resort to such measures. The underwater charges are not meant to harm the target but to chase off, if it appears to be a potential threat.
The incident comes in the wake of similar tensions after Sweden spotted suspicious underwater activities in its territorial waters last year.