The UK Ministry of Defense has a serious anti-submarine warfare capability gap, according to a report by the House of Commons Defence Committee.
The report, Defence in the High North, warns that the shortfall weakens the UK's ability to detect and track Russian submarines in the High North, the North Atlantic and waters around the UK, including areas critical to protecting the country's nuclear deterrent.
The committee recommends that the government prevent any further Type 23 frigates from leaving service until they are replaced on a one-for-one basis by new Type 26 frigates.
The Royal Navy's requirement is for 13 frigates and six destroyers, totaling 19 major surface combatants. However, the committee reports that only 11 are currently in service: five Type 23 frigates and six Type 45 destroyers, equivalent to approximately 58% of the required fleet.
The shortfall is particularly significant for anti-submarine warfare (ASW), a central component of the UK's defense posture in the High North. The navy requires eight of its 13 frigates to carry the Sonar 2087 towed array, which helps detect and track submarines operating underwater.
All five remaining Type 23 frigates are equipped with the system, leaving the navy three ships short of its stated requirement.
The committee identifies the retirements of HMS Richmond and HMS Iron Duke in mid-2026 as contributing factors. Both vessels had been equipped with Sonar 2087, and HMS Iron Duke had undergone a five-year, £103 million refit less than three years before its decommissioning.
The Ministry of Defence had also planned to fit HMS Iron Duke with the towed-array system. Had both frigates remained in service, the navy would have had seven ships equipped with the capability, according to the report.
Type 26 delays prolong capability gap
Eight Type 26 frigates are intended to assume the Royal Navy's anti-submarine warfare role, while five Type 31 frigates will provide the remaining general-purpose frigate capability.
However, delays to the Type 26 program and the aging Type 23 fleet have created a gap between the retirement of existing ships and the arrival of their replacements. The committee notes that the reported entry-into-service timetable for the new frigates has slipped from the mid-2020s. The construction schedule means that the first Type 26 ship could take up to a decade from the start of construction to its expected acceptance into service.
Under one scenario examined in the report, the number of Sonar 2087-equipped frigates could remain at five for the next three years. This scenario assumes that two Type 26 frigates being built for the Royal Navy are sold to Norway, which has ordered at least five Type 26 frigates under a deal valued at £10 billion.
Based on that scenario, the report estimates that the Royal Navy would not meet its requirement for eight towed-array-equipped frigates until 2037. The committee argues that the situation raises questions about whether the transition from the Type 23 to the Type 26 fleet has been managed effectively and whether investment in older frigates has delivered value for money, given their subsequent withdrawal from service.
In February this year, shipbuilder BAE Systems reported on the progress of the UK’s Type 26 frigate program. The company said that the final outfitting is underway on the first two ships, HMS Glasgow and HMS Cardiff, at the Scotstoun yard. Meanwhile, HMS Belfast, HMS Birmingham, and HMS Sheffield are progressing at the firm’s Govan site.
The committee recommends that the government ensure no further Type 23 frigates equipped with Sonar 2087 leave service until replacement Type 26 frigates enter service on a one-for-one basis.
The recommendation is intended to prevent the navy's anti-submarine warfare capability from declining further before the replacement fleet becomes available.
The report places the shortfall within a broader concern about the UK's readiness to defend NATO territory against a potential Russian attack later this decade. It cites warnings that Russia could be capable of attacking NATO as soon as 2030 and argues that investment in future capabilities must be accompanied by improved readiness of existing forces.
“The High North poses a major strategic challenge for the UK’s security. This is a demanding, hostile environment, and one that our greatest adversary, Russia, is seeking to dominate for military advantage," Chair of the Defence Committee, Tan Dhesi, said.
“The UK needs to be willing to address a hard truth: it does not currently have all the capabilities to operate successfully in the High North. Russian submarine and sabotage forces in the High North pose direct risks to the North Atlantic and the UK, including the nuclear deterrent. Despite this, the Ministry of Defence has accepted a serious anti-submarine warfare gap. Publicly available evidence of low availability among destroyers, frigates and attack submarines calls into question whether the UK can meet its commitments in the High North," he concluded.