Nato has mounted a major operation to counter three Russian nuclear submarines that surged into the northern North Sea, while Poland has ordered 40,000 troops to its borders and warned that Europe is closer than ever to war. As tensions with Moscow escalated, Defence Secretary John Healy ordered an RAF RC-135 Rivet Joint spy plane to monitor Russian troop concentrations on Estonia’s border.
And on Friday Nato secretary general Mark Rutte confirmed that the UK would deploy equipment on the border with Belarus, Russia and Ukraine as part of operation Eastern Sentry to deter potential Russian aggression. The submarines, part of President Vladimir Putin’s Northern Fleet, were detected by NATO undersea sensors off Norway before being tracked by allied forces.
The Royal Navy’s frigate HMS Somerset, supported by an Astute-class submarine, is believed to have led the surveillance mission. Patrol aircraft from the UK and Norway scoured the waters with sonar buoys, while tankers and a Voyager refuelling jet provided cover overhead.
Senior officials said the deployment of three submarines together – two Yassen-class attack boats and a Borei ballistic missile carrier – was highly unusual.
The Yassen is Moscow’s most advanced hunter-killer, armed with hypersonic missiles, while the Borei carries nuclear warheads and forms the backbone of Russia’s strategic deterrent.
Naval analyst Cdr Tom Sharpe, a former Royal Navy frigate commander, said the combination was striking. “There is no way a Borei would want to be detected, so if NATO has managed to pick it up and get a boat in the trail, that’s a serious intelligence gain,” he said.
“It may have been sloppy navigation rather than a show of force – but even being found forces NATO to respond, stretching resources.”
The submarine activity coincided with what Warsaw described as a deliberate Russian drone attack on Polish territory – the first direct incursion into NATO airspace since 2022. Nineteen drones crossed into Poland during overnight strikes on Ukraine, forcing the temporary closure of four airports, including Warsaw Chopin.
At least four drones were shot down over southern Poland.
Prime Minister Donald Tusk said: “This situation brings us the closest we have been to open conflict since World War Two.”
Allies are now deploying additional troops, artillery and air defence systems to reinforce Poland’s eastern flank. British officials believe Moscow is probing NATO’s defences while also staging its largest war games in years.
The drills, codenamed Zapad, involve up to 200,000 Russian personnel across an area stretching from the Kola Peninsula to Belarus, with China, India and North Korea invited to observe. Polish commanders fear the exercises may simulate an assault on the Suwałki corridor – the narrow land bridge linking Poland to Lithuania between Belarus and Russia’s Kaliningrad exclave – considered one of NATO’s weakest points.
A senior British defence source said: “Putin is flexing his military might to see how far he can push. The drone strikes were a test, and so are these submarines.”