More than a dozen vessels from 11 countries are participating in the ‘Dynamic Mongoose’ exercise.
Nato will simulate detecting and attacking submarines in one of the most hostile seas, with rugged but shallow underwater canyons, rapid currents, and high sound pollution from freshwater pouring in from Norway’s fjords.
Tensions have been running high in the region since Russia annexed part of Ukraine last year, with the three small Baltic states, which rely on the Nordics for defence, fearing they may be next as they are home to big Russian minorities.
Finland detected an unidentified submarine along its coast last week, firing depth charges at the vessel, while Nato-member Latvia, a former Soviet state, last month said it detected a Russian submarine near its waters.
Russian aircraft have also repeatedly approached and even violated Nordic and Baltic airspace in recent months, challenging air defences and triggering allied responses.
“Russia has a right to be at sea, just as we do,” Rear Admiral Brad Williamson, the commander of the exercise said. “But the incidents we have seen are not in line with international regulations and that’s been the cause of concern.”
Nordic defence ministers issued a strongly worded condemnation of Russia last month, calling it the biggest threat to security, prompting Russia to say Finland’s and Sweden’s closer ties with Nato were of “concern”.