According to analysts cited by Business Insider, NATO has stepped up its presence in the Arctic amid concerns about Russian submarine activity. The alliance is now conducting more active patrols across both the Arctic region and the North Atlantic.

The publication notes that NATO’s overall military footprint in the area — in the air, at sea, and on land — has more than doubled over the past two to three years. Observers also point out that Russia operates one of the world’s largest submarine fleets, with roughly 64 active vessels.

Colonel Martin O’Donnell, spokesperson for NATO’s Supreme Headquarters Allied Powers Europe, recently explained that Russian submarines are easier to monitor while operating in relatively shallow waters. However, once they reach the open Atlantic, tracking them becomes significantly more difficult. This challenge, he indicated, is one of the reasons behind the alliance’s growing naval activity in the Arctic.

O’Donnell also noted that NATO’s role in the North Atlantic has expanded since December, when the alliance’s new Joint Force Command in Norfolk broadened its area of responsibility to include Finland, Sweden, and Denmark. The command now oversees a new NATO deterrence mission known as Arctic Sentry.

Observers say there is an increasing recognition within NATO that the strategic importance of the Arctic and the North Atlantic is growing. As a result, the alliance is placing greater emphasis on deterrence efforts in the region.