Finland’s navy said on Tuesday it had dropped three warning charges over an unidentified object in the Nordic country’s territorial waters near the capital, Helsinki.
The incident comes six months after neighboring Sweden scrambled its maritime forces in a hunt for what was suspected to be a Russian submarine in its waters.
A Finnish defense spokesman said it was too early to tell if the object was a submarine. A full analysis of sensor data could take days, he said.
The spokesman added that it was highly unusual for charges to be used. “I have been in the navy since the 1990s and I can’t recall it happening,” Commodore Olavi Jantunen told reporters.
Jantunen emphasized that the bombs were not meant to damage the target. “The purpose is to let the target know that it has been noticed,” he told Helsingin Sanomat newspaper.
Tensions have been rising in the Baltic Sea region since Russia occupied and annexed the Crimean Peninsula from Ukraine last year. Fighter jets from Northern European countries have regularly intercepted Russian strategic bombers and planes approaching their airspace through last year.
Russia stepped up its provocations after a row with the European Union over the bloc’s improving relations with its former Soviet republic, Ukraine. Especially Eastern European states that used be in Moscow’s orbit are worried about Russian revanchism. NATO deployed troops in member states east of Germany for the first time since the end of the Cold War in a bid to reassure them.
In February, Finland and Sweden, which have stayed out of NATO, signed a military cooperation agreement that could see the two nations go to war together in the event of an attack.
Earlier, they agreed with other Northern European countries, including Denmark and Norway — which are both in NATO — to improve intelligence sharing and joint air force training.
Support for joining the Western military alliance has risen in Finland and Sweden since relations with Russia deteriorated.