A former senior NATO commander has warned that Russia's newer, quieter nuclear-powered submarines are increasing pressure on the alliance's northern defences, as Moscow expands military infrastructure across the Arctic. Retired General Philip Breedlove said the improved stealth of Russian vessels, combined with the militarisation of the Kola Peninsula, is making it harder for NATO to track submarine movements near the Northern Sea Route and the Greenland-Iceland-UK Gap, a corridor critical to monitoring access to the North Atlantic. NATO's Allied Joint Force Command Brunssum also flagged the issue publicly, describing the growing submarine threat in the region as "serious".

The concern centres on Russia's Yasen-M-class submarines, 13,800-tonne vessels fitted with advanced acoustic-quieting technology that Russian officials claim render them effectively undetectable. According to the US Naval Institute, they can carry cruise missiles with a range of around 1,000 miles, anti-ship missiles and hypersonic anti-ship weapons; Russia's Sevmash shipyard began construction of the ninth such submarine in June. Breedlove suggested Vladimir Putin may be publicising these capabilities partly to distract from setbacks in the war in Ukraine, while stressing that NATO is adapting its surveillance methods to counter the quieter Russian fleet.