achieve asuccesstul landing. Theability tolandquickly largequantities ot ammunition, petrol, oil,lUbricants, food,communications equipment, field hospitals. fieldkitchens etc.isvital. Recentyearshaveseentherapid development oftheability tousehelicopters toramphibious operations. The transportation capabilities otappropriate commercial vessels, insomecases pre-planned. canbeotsigniticant assistance insupporting suchoperations. 123.Someofthelargest amphibious shipsareabletoopendoorsattherearand tloodthesterntoprovide docking baysforsmaller landingcrafttoterryvehicles andtroops fromshiptoshore. Othersaredesigned tobe"roll-on/roll-oft" tor vehicles orarespecially strengthened toaccommodate tanks,suchastheSoviet ROGOVclassotvessel. Thelargest amphibious ships, some39,000tonsfullload, areoperated bytheUnitedStates andprovide comprehensive control otassault forces, weapons, sensors, landing craftandelectronic warfare. Attheotherend ofthescale,therearemanyindividual landingcrattofbetween 60and300tons. Alsonowbeingintroduced areair-cushion vehicles otSome150tons,gas-turbine powered andabletooperate upto3or4feetabovetheseasurface withrangesof upto500kmandspeedsinexcessof40knots. /...A/40/535 English Page40 124.Amphibious operations neednotbelarge-scale tobesignificant froma security pointofview.Therearealsolow-level operations which,carried outin coastal waters, harbours, riverestuaries etc.,mightbereferred toas "brown-water activities ".Suchactivities haveastheirpurposes amphibious infiltration, intelligence-gathering orsabotage andmayusesmalland mini-submarines, other submerg~d vehicles andswimmers. (e)Mineoperations 125.Formanyyearsoffensive mininghasbeenrecognized asoneoftheleast expensive andmosteffective meansofdenying theuseoftheseaareatoanenemy. Theminingofareasthrough whichanenemymustpassinordertoachieve his objective hasonseveral occasions hadmajorresults intheformofdisruption of theothersidelsactivities; therehavebeenrecent instances ofmineinterference withtheuseoftheworld's seasbycommercial shipping. 126.Minesmayrestdirectly onthesea-bed ormaybemooredtoit.Themethods usedtoactivate andexplode theminesestablish themascontact- or influence-mines. Theformerexplode wheninphysical contact withthetargetship orsubmarine. Thelatter areactuated bycertain influences, suchasmagnetic, acoustic orpressure effects caused bythetarget. Itisalsopossible tocreate firingsystems thatcombine anyoftheseeffects, thuspermitting smalltargets to passbutactuating whentargets ofacertain sizecomeintorange. Inaddition, minescancontain counters sothattheyremaindormant untilaspecified numberof targets haspassed. Minesmaybelaidbyaircraft, submarines orships,including merchant ships. 127.Minecountermeasures arenoteasy.Minesweeping canbeeither bymechanical means, inwhichsweepwiresarmedwithcutters aretowedbehind minesweepers and severtheminemooring cables, orbyinfluence means, inwhichdevices areusedto trickthemineintoexploding harmlessly. Mine-hunting isadifferent method, Whereby high-resolution sonarslocate andidentify underwater objects asminesor non-mines, andthentheobjects canbeexploded ordiversorremote-controlled vehicles canbeputdowntotakeappropriate action. 128.Mostnavies haveatleastlimited minesweeping ormine-hunting capacity anda fewhavesophisticated equipment. Oftheworldtotalofover1,000minesweepers andmine-hunters, ithasbeenreported thattheSoviet Unionpossesses byfarthe largest singleproportion, amounting toaboutonethirdofthetotal. TheUnited States minecountermeasures capability restslargely withsome23minesweeping helicopters, butplanshavebeenannounced tobUy44newminecountermeasures helicopters andtosupport themwithabout30minecountermeasures ships. (f)FastAttackCraft 129.Atypeotvessel whichisofparticular valuetomanycoastal naviesisthe FastAttackCraft(FAC1. Generally ofabout100to200tonsdisplacement, about 50metresinlengthandcarrying acrewofsome20to30personnel, thesecraftare comparatively inexpensive. Powered bydiesel engines orgasturbines, theycanbe hullvessels orhydrofoils andcanbecapable ofspeedsofupto55knots. Fitted /...A/40/535 English Page41 withlightguns,missiles ortorpedo tubestheycanbeusedinavariety ofcoastal roles,buttheydonothaveprolonged endurance orocean-going capacity forvery heavyweather, although thereisnowadefinite trendtowards theconstruction of largervessels. According toJane'sFighting Ships 1982~83, thereareatpresent
**Analysis**
The text appears to be a technical description of various naval vessels and equipment, highlighting their capabilities, features, and uses. It mentions the transportation of troops, equipment, and supplies, as well as the importance of mine countermeasures. The language used is formal and technical, suggesting a military or naval context. Given the focus on naval vessels and operations, it is likely that the text is related to the field of defense or military operations.

**Category**
Transport and communication, Defense