Margaret Thatcher is said to have ordered testing of a laser to be used in the Falklands War . A secret 'death ray ' laser was developed during the Falklands War and ordered for testing by the then Prime Minister Margaret Thatcher , documents reveal . Britain was said to have worked with America to develop the high powered lasers for use on the battlefield during the 1970s and 1980s . The beam , nicknamed a 'death ray ' , had been developed quickly because of fears over the weapons possessed by the Soviets - but was never used . But Lady Thatcher was said to be so impressed with the technology she ordered testing to take place during the Falklands War , the Daily Express reported . Existence of the laser was revealed in the National Archives , in a letter - marked 'top secret ' from the then Defence Secretary Michael Heseltine to Lady Thatcher in 1983 about the weapons owned by the Soviets and Britain 's position . It said : 'You may recall that we developed and deployed with great urgency a naval laser weapon , designed to dazzle low-flying Argentinian pilots attacking ships , to the Task Force in the South Atlantic . 'The weapon was not used in action and knowledge of it has been kept to a very restricted circle . ' The letter was revealed under the 30 year rule . Sheffield academic Dr David Clarke found the letter in his search of the archives and said the 'naval laser weapon ' referred to a device tested , but never used in anger , when troops were defending the Suez Canal in 1941 . Margaret Thatcher ( pictured front , centre ) visited HMS Hermes when it came back from the Falklands War . This device used powerful searchlights to dazzle pilots as they attacked Royal Navy ships . In 1982 , when the Falkland Islands was invaded , it was decided to use the same tactics to try and blind enemy pilots . In the 1980s Britain was said to be focused on developing medium power lasers directed against relatively softer targets such as eyes , optic and electro-optic sensors . These weapons was designed to target low flying aircraft by 'dazzling ' pilots targeting ships . The 'death ray ' was said to be unlikely to be unsuccessful in targeting ships but would work on humans . Britain 's laser weapon research in the 1980s was covered by two programmes - known as Raker and Shingle . According to the correspondence from Mr Heseltine , Britain had been working with America on developing laser weapons since the 1970s . Mr Heseltine also detailed fears in his letter to Lady Thatcher about the Soviets were developing a range of secret beam weapons . However he said he was uncertain whether owning these weapons was useful . In the letter he added : 'the Russians could be in a position to field such weapons by the mid-1980s ( in fact , the Russians may already have deployed a laser weapon on the cruiser Kirov ) ' . The Falklands War lasted from April to June 1982 , with the loss of 255 personnel from the UK .
America believed to have worked with Britain on development of lasers . Michael Heseltine wrote a 'top secret ' letter to Margaret Thatcher in 1983 . It told of fears about the Soviets developing lasers and America 's progress . Letter revealed America had its own 'naval laser weapon ' to dazzle pilots . Margaret Thatcher ordered tests during Falklands War but it was not used .