d.ifferent weapon types, some mrlti-purpose, others intended for special obJectives" This is also covered- to some er:tent in what fo11olls, Warhead. d.esipn and characteristic s 73, The single most outstanding feature in warhead d.eveloluent up to now has been the red.uction of slze and veight in rel-ation to yield. This process has nade possible the d.es1gn of multiple uarheads on stlategic nissiles, as well- as some of the weapons denoted as tactical. ?l+" The bonbs that l"evefl-ed- Hiroshina and. Nagasaki weighed. about 5 tons each and could not have been d.elivered by any other carriers than heaw bonbers. By comparison, the Poseidon submarine-launched nissi"le, lrith a total throw-iteiGht of f ,OOO ke., earries 10 varhcad.s, each of three times the yield of lliroshina bonb ' Tnis represents a l-5O-fofd increase in the yicld-to-veight ratio' 7r" Another example is Siven by the nuclear artillery sheLls mentioned' in cnapter II , which denonstrabe that it is possible to buifd nuclear explosives so si.rafl that the outer d.ia;areter of the casing is -155 r.rlr. J and so li8ht that the explosive, its a.sscciatecl safecy, ar..rirrE and fjring *.cchanisrns .rnd the n(-tr.l casiu: altogether do not we iilh :r."rch more than 40 kg., -"/hich is the approximate ueia'ht of a conventional 155 rnrn, she1r.!,/ 35 / 392 English Annex fagt Jr) 7b. From ilvaifable data on MIRVs and other devices, it seerns 1ike1y that, at -Lcasr in the United Stares, bhis I'niniatur i zat ion " of nuc.Iear uarheads is now, in sone applications" close to the limits set by the .Iaws of physics. Other nuclear- weapon States rr:)ay be a-pproaehing - or alreafir have acbieved. - the sa.me levels of ^^*-r-l.,arc h,-+ +har, --v alq^ nrrt lhFiT nrinriti^c ,lj efFr.-nj-lw Ac hes been indicated earlier, the Soviet Union has developed MIRV technology.