GIUK gap

The GIUK gap is the maritime chokepoint formed by sea lanes between Greenland, Iceland and the United Kingdom, the primary corridor through which Russian submarines must transit to reach the open Atlantic. Around 18 active submarine cable systems route through the gap, carrying roughly 97% of transatlantic internet traffic.

During the Cold War, NATO's SOSUS hydrophone arrays gave persistent tracking of Soviet submarines here at a lifecycle cost of roughly $2bn over 30 years, before budget cuts wound the network down between 1991 and 1998. By 2020 IISS assessed NATO maritime patrol aircraft coverage had fallen to fewer than six sorties a day, down from 24 at Cold War peak, a gap the 2023 Balticconnector pipeline rupture and BT Shetland cable severing, both attributed to anchor drag near Russian naval exercises, exposed as a monitoring blind spot.

NATO's Task Force X-Arctic, launched 6 June 2026 aboard NRV Alliance, is the alliance's attempt to restore that surveillance using DIANA-selected uncrewed systems. The gap recurs across Lowdown's coverage of European energy security, the Russia-Ukraine war and maritime autonomy alike, given its dual role as military chokepoint and critical-infrastructure corridor.