over6,000. TheUSSTheodore Rooseve1t. thefourthshipofitsclass,isat present beingbuiltandisexpected tocostwellover$2billion. TheSoviet Union hasbeenreported 191tobeconstructing itsfirstlargeaircraft-carrier ina shipyard ontheBlackSea.Believed tobenuclear-powered andabout65,000tons, theshipwillreportedly beabletocarryabout60aircraft. 115.Conventionally powered aircraft-carriers carryseveral thousand tonsoffuel oil.Inordertoprovide greater windoverthedeckWhenoperating, theShips oftenhavetoproceed atclosetomaximum speed,andtheirconsequent highfuel consumption ratesnecessitate refuelling atseaeveryfewdays.Nuclear-powered aircraft-carriers require reactor refuelling every10to13years, andtherefore theiroperational endurance depends moreonthefuelconsumption rateSoftheir aircraft andtheconsequent needtoreplenish ship-borne supplies. 116.Fullyeauipped withaircraft catapults andarresting gear,large aircraft-carriers aresocostlythatthemajority ofnavies whichpossess themare obliged toforgotheirreplacement, notwithstanding theiradvantages. Ifthe present trendcontinues, inseveral yearsonlythreeStateswillretainsuch ships. However, thisdoesnotsignify theendofsea-borne airpower forother countries. Aworthwhile replacement solution isthemuchlesscostly helicopter-carrier whichcanalsooperate aircraft capable ofvertical orshort take-off andlanding (V/STOLj. Theperformance oftheseaircraft hasimproved considerably inrecentyears. Several countries already havetheminservice and morecountries Seemlikelytoacquire them. 117.Theimportance ofnavalaviation continues toincrease withthegrowthof aircraft anti-ship missiles whichhavedemonstrated theirpossibilities inrecent conflicts. Moreandmorecountries haveequipped themselveS withsuchweapons whichpresent amajorthreattoallShipsoutto200or300kmfromthecoast. On theotherhand,several maritime States havelong-range maritime patrolaircraft capable ofsustained endurance andoftracking theirtargets overawideseaarea. Someofthesetraditionally anti-submarine aircraft arenowbeingequipped with missiles, giving themananti-ship capability andadditional defences against surface vessels. (c)Submarines 118.Theunderwater speedandendurance ofconventionally powered submarines is strictly governed bytheavailable powerfromelectric batteries whichhavetobe recharged bydieselgenerators everyfewdays,forwhichthesubmarine hasto snorkel orsurface. However, withnuclear submarines thisisnotthecase,asthey areabletooperate without theneedtosurface atfreauent intervals, and underwater patrols arelimited morebyotherfactors suchasfoodandairforthe crew. ThUS,nuclear SUbmarines canremain submerged forovertwomonths, operate I...A/40/535 English Page39 undericeforlongperiods orcircumnavigate theworldwithout surfacing. Nuclear submarines arealsocapable ofmuchhigherunderwater speedsthanconventional submarines -atbest.OVer40knotscompared withabout21knots. 119.Forthemostpart,ballistic missile submarines arenuclear-powered. Formany yearstheSoviet Unionhasalsodeployed various classes ofcruisemissile submarines, firstconventionally propelled andthennuclear-propelled. carrying missiles withrangesofupto650km. 120.Mostsubmarines areattacksubmarines, equipped tohuntanddestroy either shipsorothersUbmarines. Allfivenuclear-weapon States haveboth nuclear-powered andconventionally powered attacksubmarines inservice. although inthecaseoftheUnitedStatesalmostallitssubmarines arenuclear-powered. At present, allotherStates haveonlyconventional submarines. 121.Inaddition tothe111SSBNsshowninparagraph 102above.itisestimated thattherearemorethan800othersubmarines (inroundnumbers, morethan 200nuclear andsome600conventional) serving inthenaviesottheworld. Atthe opposite endofthescaletramtheverylargesubmarines, thereareverysmall submarines withcrewsofonlytwoorthreeandusedforinshore operations. There arealsounmanned bottom-crawling devices thatoperate onthesea-bed. (d)Amphibious forces 122.Thetroopsinvolved inamphibious assaults areoftenmarines. SomeStates regardsuchtroopsaspartotnavalstrength, someregard themasarmypersonnel andothersconsider themseparate tromeither. Amphibious operations ottenrequire vessels withquiteditferent capabilities tromthoseinvolved inpurelynaval operations. Theymustbeabletocarryheavyequipment, including tanks.and accommodate largenumbers ottroopswiththeweapons andothersupplies neededto
**Analysis**
The text appears to be discussing the capabilities and characteristics of various types of naval vessels, including aircraft carriers, submarines, and amphibious forces. It also touches on the importance of naval aviation and the potential threats posed by anti-ship missiles. The text does not seem to be focused on economic development, natural resources, agriculture, forestry, fishing, industry, transport, communication, international trade, health, education, employment, humanitarian aid, or culture. Instead, it appears to be primarily concerned with the scientific and technological aspects of naval warfare.

**Category**
Science and technology