United Kingdom and weapons of mass destruction The United Kingdom has possessed weapons of mass destruction , including nuclear , biological , and chemical weapon s . The United Kingdom is one of the five official nuclear weapon states under the Nuclear Non - Proliferation Treaty and has an independent nuclear deterrent . The U . K . has been estimated to have a stockpile of approximately 160 active nuclear warheads and 225 nuclear warheads in total . The United Kingdom renounced the use of chemical and biological weapons in 1956 and subsequently destroyed its general stocks . Nuclear weapons . The United Kingdom has four " Vanguard " class submarines armed with nuclear - tipped Trident missile s . The principle of operation is based on maintaining deterrent effect by always having at least one submarine at sea , and was designed during the Cold War period . One submarine is normally undergoing maintenance and the remaining two are in port or on training exercises . It is believed that British ballistic missile submarine patrols are coordinated with those of the French . Each submarine carries up to sixteen Trident II D - 5 missiles , which can each carry up to twelve warheads , for a maximum of 192 warheads per sub . However , the British government announced in 1998 that each submarine would carry only 48 warheads ( halving the limit specified by the previous government ) , which is an average of three per missile . However one or two missiles per submarine are probably armed with fewer warheads for " sub - strategic " use causing others to be armed with more . The British - designed warheads are thought to be selectable between 0 . 3 kilotons , 5 - 10 kt and 100 kt ; the yields obtained using either the unboosted primary , the boosted primary , or the entire " physics package " . The United Kingdom has purchased the rights to 58 missiles under the Polaris Sales Agreement ( modified for Trident ) from the United States Navy ' s " pool " . These missiles are fitted with United Kingdom - built warheads and are exchanged when requiring maintenance . Under the agreement the United States was given certain assurances by the UK regarding the use of the missiles , however the United States does not have any veto on the use of British nuclear weapons . The United Kingdom is one of the five " Nuclear Weapons States " ( NWS ) under the Nuclear Non - Proliferation Treaty , which the UK ratified in 1968 . The UK permits the U . S . to deploy nuclear weapons from its territory , the first having arrived in 1954 . During the 1980s nuclear armed USAF Ground Launched Cruise Missile s were deployed at RAF Greenham Common and RAF Molesworth . As of 2005 it is believed that about 110 tactical B61 nuclear bomb s are stored at RAF Lakenheath for deployment by USAF F - 15E aircraft . In March 2007 , the UK Parliament voted to renew the country ' s Trident nuclear submarine system at a cost of £20bn . In July 2008 , " The Guardian " claimed that the decision had already been made to replace and upgrade Britain ' s nuclear warhead stockpile at a cost of £3bn , extending the life of the warheads until 2055 . Chemical weapons . The UK was a signatory of the Hague Conventions ( 1899 and 1907 ) which outlawed the use of poison gas shells , but omitted deployment from cylinders probably because it had not been considered . However , during the First World War , in retaliation to the use of chlorine by Germany against British troops from April 1915 onwards , British forces deployed chlorine themselves for the first time during the Battle of Loos on 25 September 1915 . By the end of the war , poison gas use had become widespread on both sides and by 1918 a quarter of artillery shells were filled with gas and Britain had produced around 25 , 400 tons of toxic chemicals . Britain used a range of poison gases , originally chlorine and later phosgene , diphosgene and mustard gas . They also used relatively small amounts of the irritant gases chloromethyl chloroformate , chloropicrin , bromacetone and ethyl iodoacetate . Gases were frequently mixed , for example " white star " was the name given to a mixture of equal volumes of chlorine and phosgene , the chlorine helping to spread the denser but more toxic phosgene . Despite the technical developments , chemical weapons suffered from diminishing effectiveness as the war progressed because of the protective equipment and training which the use engendered on both sides . See Use of poison gas in World War I . After the war , the Royal Air Force dropped mustard gas on Bolshevik troops in 1919 , and Winston Churchill , secretary of state for war and air , suggested that the RAF use it in Iraq in 1920 during a major revolt there . Historians are divided as to whether or not gas was in fact used . The UK ratified the Geneva Protocol on 9 April 1930 . The UK signed the Chemical Weapons Convention on 13 January 1993 and ratified it on 13 May 1996 . Many ex - servicemen have complained about suffering long term illnesses after taking part in tests on nerve agents . It was alleged that before volunteering they were not provided with adequate information about the experiment s and the risk , in breach of the Nuremberg Code of 1947 . Alleged abuses at Porton Down became the subject of a lengthy police investigation called Operation Antler , which covered the use of volunteers in testing a variety of chemical weapons and countermeasures from 1939 until 1989 . An inquest was opened on 5 May 2004 into the death on 6 May 1953 of a serviceman , Ronald Maddison , during an experiment using sarin . His death had earlier been found by a private MoD inquest to have been as a result of " misadventure " but this was quashed by the High Court in 2002 . The 2004 hearing closed on 15 November , after a jury found that the cause of Maddison ' s death was " application of a nerve agent in a non - therapeutic experiment " . Biological weapons . During the Second World War , British scientists studied the use of biological weapons , including a test using anthrax on the Scottish island of Gruinard which left it contaminated and fenced off for nearly fifty years , until an intensive four - year programme to eradicate the spores was completed in 1990 . They also manufactured five million linseed - oil cattle cakes with a hole bored into them for addition of anthrax spores between 1942 and mid - 1943 . These were to be dropped on Germany using specially designed containers each holding 400 cakes , in a project known as Operation Vegetarian . It was intended that the disease would destroy the German beef and dairy herds and possibly spread to the human population . Preparations were not complete until early 1944 . Operation Vegetarian was only to be used in the event of a German anthrax attack on Britain . Offensive weapons development continued after the war into the 1950s with tests of plague , brucellosis , tularemia and later equine encephalomyelitis and vaccinia viruses ( the latter as a relatively safe simulant for smallpox ) . In particular five sets of trials took place at sea using aerosol clouds and animals . The programme was cancelled in 1956 when the British government renounced the use of biological and chemical weapons . It ratified the Biological and Toxin Weapons Convention in March 1975 .