The Royal Navy’s Carrier Strike Group is a hollow force


The Royal Navy’s Carrier Strike Group is a hollow force

17 February 2025 10:44am GMT Later this spring, over 150,000 tonnes of steel and several thousand military personnel will leave British waters, to sail halfway round the world and back. With the Royal Navy’s carrier strike group (CSG) at its heart this deployment – CSG25 – is intended to send a strong message on the UK’s military capabilities, as well as supporting the government’s objectives on trade and diplomacy. But it could be affected by what successive Defence Secretaries have referred to as the “hollowness” of the UK military. A fully-formed and equipped carrier strike group is a potent military capability, able to act as a platform for diplomacy even while it prepares to launch strikes on adversaries, or operates and exercises alongside partners. It’s capable of travelling thousands of miles providing its own protection against any threat, carrying its own fuel and supplies. Central to the CSG are the aircraft carrier and its carrier strike air wing, surrounded by vessels able to defend against attack from enemy aircraft and missiles, or detect and push back hostile surface ships and submarines. The group has the ability to strike targets at sea or on land. The UK doesn’t try to match the power of the US Navy’s carrier groups; rather the Queen Elizabeth class carriers represent an attempt to develop a national capability that provides significant combat power for national interests or in support of Nato Allies.CSG25 is the second global deployment of the group, following CSG21 – Operation FORTIS – which was a major event for the UK, given the long gap since its previous carriers were retired in 2011. It involved the deployment of HMS Queen Elizabeth, a squadron of F-35B stealth aircraft, two Type 45 destroyers for air defence, two Type 23 frigates for anti-submarine warfare, a tanker, a solid stores ship, and on occasion an Astute-class submarine. In addition, a squadron of US Marine Corps F-35Bs were embarked, and the group was joined by a US Navy destroyer and a frigate from the Dutch Navy. One of the central points of the CSG is to provide a “sovereign capability”: a UK force that can operate by itself or can be offered in support of others without bringing a bill. In 2021 the presence of the US and Dutch forces demonstrated how other countries could be integrated into the group, but they were not critical to its operation. Having US jets on board added a useful deterrent factor, but the UK would never want to make that a necessity when deploying its own carrier. Of course, UK military deployments also benefit from intelligence from other countries, or coordinated cyber defences, and the use of partners’ facilities (Guam is one example from CSG21) but the UK CSG is intended to be a national capability. The signs are that CSG25 will face three challenges to this: the Royal Navy escort force has shrunk; the support provided by the Royal Fleet Auxiliary is fragile; and the F-35B force continues to grow very slowly. First, it isn’t clear how large the CSG will be this time round. CSG21 was a “full fat” deployment, with multiple layers of protection, including international partners. A large CSG can conduct more simultaneous activities and doesn’t just move as a single “package”; it can operate over thousands of square miles, potentially launching strike operations even while individual escorts can detach to conduct a port visit or other operations. For example, in 2021 HMS Defender was operating in the Black Sea while the main group was launching aircraft into Iraq and Syria against Daesh. Additional escorts mean additional resilience; HMS Diamond developed a fault during CSG21 which needed repairs, but the group still had UK protection from HMS Defender. The four UK escort warships in CSG21 came from a total fleet of 18 (albeit not all were active). The Royal Navy has generally argued 19 are necessary to meet its commitments, but the 2021 deployment could just about be managed, leaving a frigate based in the Gulf and other ships to protect home waters or for tasks that emerged at short noticeSince 2021, the escort force has shrunk to 14 ships at different levels of readiness; the six Type 45s and eight Type 23s. Assuming the Navy sticks to the tough but (just) achievable ratio of one in three ships deployed at any given time, sending four escorts would constitute the overwhelming bulk of the available Royal Navy surface force and probably only leave one (at a push two) available for all other eventualities.