Britain faces serious gaps in its ability to defend the High North against Russian submarine and underwater threats, with potential consequences for the UK's nuclear deterrent, vital undersea cables and transatlantic supply routes, MPs have warned.
In a report published on 22 October 2026, the House of Commons Defence Committee said weaknesses in anti-submarine warfare and the availability of Royal Navy vessels raised questions about whether Britain could meet its military commitments in the Arctic and North Atlantic.
Shortfall in submarine-hunting frigates
The committee highlighted a reduction to five frigates equipped with towed-array sonar, compared with a stated requirement for eight. The equipment is used to detect and track submarines. MPs questioned whether the transition from the Type 23 frigates to the incoming Type 26 vessels had been adequately managed.
The committee recommended that no further sonar-equipped Type 23 frigates should leave service until they can be replaced on a one-for-one basis by Type 26 ships. It also raised concerns about the availability of destroyers, frigates and attack submarines.
Under-ice capability and critical infrastructure
The report said the UK had allowed its submarine under-ice operating capability to lapse as the High North became increasingly strategically important. MPs warned that this could give Russian submarines greater freedom to operate beneath Arctic ice, potentially threatening NATO sea lanes, undersea communications cables, energy pipelines and Britain's nuclear deterrent.
The committee distinguished risks during peacetime, particularly to underwater infrastructure, from the potentially wider consequences in a conflict. It did not conclude that Britain's nuclear deterrent had already been compromised or that any specific attack on UK infrastructure was imminent.
Call to reassess Britain's northern defence commitments
MPs also urged the government to reassess the role of the UK-led Joint Expeditionary Force, including whether it should concentrate more heavily on threats in the High North and operate more closely alongside NATO. They said Britain might need to consider expanding its Army presence in Estonia to brigade strength if resources were redirected from the Baltic region.
Defence Committee chair Tan Dhesi MP said the UK did not currently possess all the capabilities needed to operate successfully in the High North and pointed to the Ministry of Defence's acknowledgement of a serious anti-submarine warfare gap.
The findings are parliamentary committee assessments and recommendations, rather than new government procurement or deployment decisions. The government has yet to respond formally to the report.