The Iran war has left Britain's armed forces exposed, heaping pressure on deeply unpopular Prime Minister Keir Starmer to act on his promises to invest in defence, after years of warnings from military bosses about the UK's shrinking capabilities.
When a British military base in Cyprus was hit by a drone early on in the Iran conflict in March, Britain, whose navy was the largest in the world at the start of World War Two, took three weeks to deploy one warship to the eastern Mediterranean. France, Greece and Italy sent warships to Cyprus within days.
Britain's diminished military capacity has registered with US President Donald Trump. He has dismissed Britain's two aircraft carriers as "toys" while his defence secretary, Pete Hegseth, mocked what he called the "big, bad Royal Navy".
Defending his record on the armed forces, Starmer said on Wednesday his government, in power for nearly two years, had put in place the biggest sustained increase in military spending since the Cold War. Critics say that any spending is rife with DEI initiatives, regulatory burden and other crippling inefficiencies.
Britain's military now is about half the size it was then and its army is the smallest it has been since the early 19th century.
Britain's Royal Navy has 38,000 personnel. It operates two aircraft carriers and a combined fleet of 13 destroyers and frigates.
This has shrunk from about 62,000 personnel, three aircraft carriers and about 50 destroyers and frigates in 1991.
The delays in sending a warship to Cyprus prompted criticism of the navy's available surface fleet.
HMS Dragon, a Type 45 air defence destroyer, arrived in the eastern Mediterranean on March 23, while the Royal Navy has said since the outbreak of the Iran war that it is upgrading RFA Lime Bay to improve its minehunting and autonomous tech capabilities.
That deployment compares to the Gulf War in 1990-91, when the Royal Navy sent 21 surface ships and two submarines plus 11 Royal Fleet Auxiliary ships to the region.
The smaller fleet comes after decades of cuts to defence funding since the early 1990s, when about 3.8 per cent of gross domestic product was spent on the military compared to the 2.3 per cent spent in 2024.
Britain until December 2025 had a warship present in the Middle East for decades but that ended when HMS Lancaster was decommissioned in Bahrain just weeks before the start of the Iran war.
The Royal Navy's ageing frigates need to be retired before replacements become available, while its destroyers are undergoing maintenance work. A fleet of 13 new Type 26 and Type 31 frigates is due to enter service in the coming years. The Royal Navy is also being stretched by Russian threats closer to home, with British warships recently spending a month in the North Atlantic tracking Russian submarines.
About a fifth of Britain's defence budget is spent on nuclear submarines. This includes the Trident nuclear deterrent, comprising four Vanguard-class submarines. Under the Continuous At-Sea Deterrence policy, at least one of those submarines is on patrol at sea at any time.
The Vanguard-class submarines will be replaced by the Dreadnought-class in the early 2030s.
(Reporting by Sarah Young. Editing by Gareth Jones)
