The forthcoming strategic defence review (SDR) in 2025 is expected to outline the future direction of the UK’s armed forces and the capabilities it needs to fulfil the demands placed on it. About this briefing This briefing, one of a series on UK armed forces capabilities, looks at the surface fleet of the Royal Navy and Royal Fleet Auxiliary, including frigates, destroyers, and support ships (information on submarines can be found in Commons Library briefing UK submarine fleet). It provides information on current numbers, brief histories of procurement (where relevant) and future vessel plans, as known prior to the publication of the strategic defence review. It highlights concerns about capability gaps and the size of the fleet but it does not cover personnel numbers. An inventory of equipment does not reflect the true capabilities of the British armed forces. However, the numbers, mix and type of vessels reflect the UK’s ambitions for the armed forces and guide the types of operations it can conduct or participate in. An overview of major operations can be found in Commons Library briefing UK armed forces operational commitments. The UK’s air capabilities are examined in Library briefing UK defence in 2025: aircraft fleets. This briefing will be updated to reflect any decisions made by the Defence Secretary in the SDR. The SDR is expected to be published in spring 2025; the government has not given a firm date for publication.