nuclear-weapon States" and in par-ticulax the two super-Powers r have withhcld their participation in the work of the Group of Experts. fhe Chairman of the Group has nevertheless kept the super-Powers inforued. of the p"eparation of this report. 7" One basic difficulty in the work on this report has been the absence, in many casese of offieially availabl-e data on nuclear weapons and xelated questions" fn consequence the Croup has in several- instances relied on other avail-able d-ata' in each instance providing the relevs.nt ?eference in order to facil-itate for the reader an understsJrding of the factua^l basis of the report. B" The present report is organized in eight chapters. Chapters If to fV are of a technical nature and refer to existing and future nuclear-weapon capabilities as irel] as the effects of nucfea.r veapons. Chapter V to VII eontain a description and aralyses of the inplications for security and. tlisarnament of the development of nucl-ear weapons as rreu. as the d-octrines for their use" A concluding sulnuary appears in chapter VIII. ;\ppendix I contains o tcchrlica-l. descrirtion of nuclcar- weapon effects, anrJ" appendix rI sets forth "Security assurances" by the nuclear- weapon States as presented to the Conmittee on Disarmanent in 19{J0.Al 35 / lr? .i, L.':. t':1i r.)rii.rc,Lil CHAPTER I] I'ACTUAL I1IFORMATIO1I ON PRESII,T I\\JCI,EA]I ARSENAI,S 9. The exact number of nuclear warheads in the vorld today is probably not knoun by any single person or institution ' and estinates cannot be verified officially. Published figures indicate " however, that the total nay be in excess of l+0,000. fn explosive power these warheads are reported to ralge from about :1.00 tous up to nore than 20 niuion tons equiva.lent of chenical high explosive. The largest weapon evex tested refeased an energy approximately 4,000 +.imes that