Anti - handling device An anti - handling device is an attachment to or integral part of a landmine or other munition e . g . some fuze types found in general purpose air - dropped bombs , cluster bombs and sea mine s . It is designed to prevent tampering . When the protected device is disturbed , it detonate s , killing or injuring anyone within the blast area . There is a strong functional overlap of booby trap s and anti - handling devices : a munition with an anti - handling device fitted has , for all intents and purposes , been booby - trapped . Purpose . Anti - handling devices serve two military purposes : Anti - handling devices greatly increase the impact of munitions on civilian populations in the areas in which they are used because their mechanisms are so easily triggered . An unexploded bomb may or may not detonate if it is lifted or overturned , whereas an anti - tank mine with an anti - handling device fitted is almost guaranteed to detonate if it is lifted / overturned , because it is specifically designed to do so . Additionally , munitions fitted with anti - handling devices increase the difficulty and cost of post - conflict clearing operations , due to the inherent dangers of attempting to render them safe . Not all munitions will have an anti - handling device fitted or enabled . Perhaps one in ten antitank mines in a large defensive minefield will have boobytrap firing devices screwed into their secondary fuze wells . Even so , deminers and EOD personnel are forced to assume that all items they encounter may have been boobytrapped , and must therefore take extra precautions . This has the effect of significantly slowing down the clearance process , even allowing for the fact that the anti - tank mines in question may be interspersed with various different types of minimum metal antipersonnel mines such as the VS - 50 or TS - 50 , some of which can also have anti - handling features . History . Technology to incorporate sophisticated anti - handling mechanisms in fuzes has existed since at least 1940 e . g . the Luftwaffe ' s ZUS - 40 anti - removal fuze ( of which 3 slightly different versions existed ) which was used during the London Blitz and elsewhere . ZUS - 40s were designed to fit underneath most Luftwaffe bomb fuzes . When a delayed - action bomb containing a ZUS - 40 was dropped on a target , the massive jolt after it hit the ground freed a ball - bearing inside the ZUS - 40 , thereby arming a spring - loaded firing pin . However , so long as the main bomb fuze remained inside its fuze well , the cocked firing pin in the ZUS - 40 was prevented from springing forward . ZUS - 40s were often fitted underneath a type 17 clockwork long delay fuze , which gave up to 72 hours delayed detonation . Rendering safe a type 17 fuze was normally a simple and straightforward process i . e . unscrew the fuze locking ring , remove the fuze from its pocket in the side of the bomb and unscrew the gaine . However , fitting a ZUS - 40 underneath a type 17 fuze made the render - safe process much more complicated and dangerous . Removing the main time - delay fuze more than a centimetre from its fuze pocket ( without neutralising the anti - handling device underneath ) automatically released the cocked firing pin inside the ZUS - 40 , which sprang forward to strike a large percussion cap , thereby causing detonation of the bomb and the death of anyone kneeling beside it . Because the ZUS - 40 was designed to be concealed underneath a conventional bomb fuze , it was very difficult to know whether a particular bomb was fitted with an anti - handling device or not . In any case , many electrically fired German bomb fuzes ( which could be fitted above a ZUS - 40 ) already had a tiny pendulum - based " trembler " device inside them , which closed the circuit and triggered detonation if the bomb was subjected to rough handling . Some German anti - handling fuzes were even more sophisticated and therefore particularly dangerous to EOD personnel e . g . the type 50 and 50BY fuzes . These were normally fitted to 250 / 500 kg bombs and contained two mercury tilt switch es which detected movement across vertical and horizontal axes . The fuzes fully armed themselves approximately 30 seconds after hitting the ground . Subsequently , if the bomb was moved in any way , the mercury switch completed an electrical circuit and triggered detonation . To complicate matters still further , German bombs could have two separate fuze pockets fitted , with different fuze types screwed into each one . As a result , one bomb could incorporate two separate anti - handling devices working independently of each other e . g . a type 17 clockwork fuze with a ZUS - 40 hidden underneath it screwed into one fuze pocket , and a type 50BY in the other . Even comparatively small air - dropped munitions could incorporate an anti - handling feature e . g . the type 70 fuze fitted to Butterfly bomb s . However , fuzes with an integral anti - handling feature were not only found in air - dropped bombs . For example , the T . Mi . Z . 43 fuze ( dating from 1943 ) fitted to Teller mine s automatically triggered detonation if ( in an attempt to render the mine safe ) the pressure plate was unscrewed . Although the designs of these anti - handling fuzes varied , all were specifically designed to kill bomb disposal personnel who had the task of rendering them safe . Allied forces developed their own designs of anti - handling devices during World War II . For example , the American M123A1 , M124A1 , M125 and M131 series of chemical long delay tail - fuzes ( which remained in service until circa 1960s ) were used in air - dropped bombs . Frequently fitted to M64 ( 500 lb ) , M65 ( 1000 lb ) and M66 ( 2000 lb ) general - purpose bomb s , these fuzes were primarily designed to operate as chemical long - delay fuzes , with settings ranging between 15 minutes and 144 hours . The time delay mechanism was simple but effective : after being dropped from the aircraft a small propellor at the rear of the bomb revolved , gradually screwing a metal rod into the fuze , crushing an ampoule of acetone solvent contained within it . When this happened the fuze was fully armed and the timer countdown had started . The acetone soaked into an absorbent pad next to a celluloid disk which held back a spring - loaded firing pin from a percussion cap connected to an adjacent detonator . Acetone slowly dissolved the celluloid disk , gradually weakening it until the cocked firing pin was released and the bomb detonated . The time delay of the fuze varied according to the acetone concentration and the thickness of the celluloid disk . Removing a chemical long delay fuze from a bomb after it had been dropped would have been a straightforward process had it not been for the fact that there was an integral anti - withdrawal mechanism designed to kill anyone who tried to render the bomb safe : fuzes such as the M123 ( and its derivatives ) contained a tiny ball - bearing at the lower end which slid out of a recess when the fuze armed itself a few seconds after being released from an aircraft . The ball - bearing jammed into the screw - threads inside the fuze well , preventing the fuze from being removed . Because the lower end of the fuze was locked in place deep inside the bomb ( where it was hard get at ) this posed major problems for enemy EOD personnel : attempting to unscrew a fully armed chemical long - delay fuze caused it to split into two separate fuze assemblies i . e . upper and lower . This action automatically triggered detonation by releasing the cocked firing pin in the lower fuze assembly , with lethal results for anyone nearby . Although many decades have passed , unexploded bombs dating from World War II with chemical long - delay fuzes fitted remain extremely hazardous to EOD personnel . This is because corrosion makes the fuze mechanism ( which is still holding back the spring - loaded firing pin from a percussion cap ) much more sensitive to disturbance . There is a high risk that even minor movement ( e . g . gently rotating the bomb casing to gain better access to the rear end ) will release the firing pin . For example , an unexploded 500 kilogram allied bomb fitted with a chemical long - delay fuze killed 3 German EOD personnel and severely wounded 6 others in June 2010 , whilst they were preparing to render it safe . Another allied bomb fitted with a chemical long - delay fuze was discovered in Munich during August 2012 , and had to be detonated in situ ( shattering windows over a wide area and causing major damage to surrounding buildings ) because it was considered too dangerous to disarm . The British " Number 37 Long Delay Pistol " ( used by RAF Bomber Command during World War II ) was another chemical long delay fuze which used a very similar type of anti - removal mechanism . A later design of British nose fuze called the number 845 Mk 2 operated purely in anti - disturbance mode . It contained a mercury switch which triggered detonation if the bomb was moved after a 20 second arming delay , which started when the bomb hit the ground . Since then , many nations have produced a wide variety of munitions with fuzes which incorporate some form of anti - handling function , including very small weapons such as cluster bombs . Alternatively , they have produced munitions with features which make it very easy to add an anti - tamper function e . g . extra ( but empty ) threaded fuze wells on anti - tank landmines , into which the detonator s on booby - trap firing devices ( plus booster attachments ) can be screwed . Classes of anti - handling devices . US Army field manual FM 20 – 32 classifies four classes of anti - handling devices : Types of anti - handling fuzes . The different classes of anti - handling devices are normally created using a variety of fuzes . This is a list of the types of fuzes used as anti - handling devices :