No fewer than ten Russian submarines, eight of which are confirmed to be nuclear powered, are said to be conducting a large-scale exercise in the frigid waters of the North Atlantic. This series of drills could potentially last months, and thus far has been centered around the Greenland, Iceland, United Kingdom Gap (commonly referred to as the GIUK Gap) — a strategically important funnel point between the majority of Russia’s ports and the open Atlantic.

The GIUK Gap is heavily monitored by NATO forces who recognize the value of the choke point in terms of both defensive and offensive seaward operations. Russian submarines are likely conducting two different types of training in the region: a defensive posture in the GIUK Gap would allow Russian submarines to protect their home ports from American subs and surface vessels, using the natural bottleneck of the area to minimize the amount of space they’d need to defend. Conversely, Russian submarines will undoubtedly train to work through the gap as quietly as possible, hoping to evade detection for potential offensive operations in the future.

Russia’s ongoing submarine drills appear to be the largest confirmed sub exercises conducted by the Russian Navy since the Cold War — though Russian officials have claimed to have conducted other large drills along America’s eastern seaboard in recent years — even claiming to have parked Akula class attack subs just outside of American Navy ports in 2017. The United States chose not to respond to those claims, likely because acknowledging them (if they did exist) would be admitting a failure of America’s defense apparatus, and denying them would just make the U.S. look like it had failed to spot the Russian subs while they were here. The U.S. Navy did, however, announce that they would bring the 2nd Fleet back out of mothballs shortly thereafter — whose area of operation is the Atlantic.

Currently, Norwegian intelligence has claimed to have a good idea where at least some of the ten submarines are currently operating, but they have acknowledged that as drills progress, it will likely get more difficult to keep tabs on them. The U.K. Navy just received its long-awaited fleet of nine Poseidon MRA Mk1 (P-8A) Poseidon sub hunting aircraft last week, which, once operational, will greatly bolster NATO’s ability to keep tabs on Russia’s undersea operations. Nonetheless, it seems likely that at least some of Russia’s submarines will find their way through the gap undetected, adding increased importance to America’s already overtaxed submarine fleets and new sub-detection technologies that are currently under development in places like DARPA.

According to Norwegian news outlet NRK, the positions of the detected Russian subs are currently:

• Two nuclear submarines are west of the Bear Island, between Svalbard and Finnmark, the northernmost part of mainland Norway.
• Two submarines are south and east of the Bear Island, guarding the entrance to the eastern part of the Barents Sea.
• Two Sierra-class nuclear submarines are training in the northern part of the Norwegian Sea.

These drills, while obviously meant to hone the Russian Navy’s ability to conduct wartime operations against NATO forces, are likely also meant as a message to Western powers. Russia’s surface navy has lost a great deal of luster in recent years, particularly since the sinking of the nation’s only dry dock that’s large enough to get their lone aircraft carrier back into service. Since then, the Russian government has invested heavily in its submarine fleets. After years of operating poorly maintained Soviet-era technology, Russia wants to ensure the world recognizes their escalating undersea power.