NARA 0313194192 REPRODUCED RT THE NATIONAL ARCHVES Cw gf im3iXJJP3 - In - or STATE ii 20520 1 SECRET 5 4 march 13 1970 MEMORANDUM 3 T0 The Under Secretary THROUGH is s FROM PM Ronald Ixfgpiers SUBJECT Preferred Limitations in SALT We believe that US security interests would be best served - by a MIRV ban and very low ABM levels in SALT This does not mean a decision to that effect need be taken before Vienna or that such an agreement would be feasible there it does mean that the Delegation should be instructed to keep Open the Option of a MIRV ban and to probe fully the Soviet position on controlling MIRVs while moving at Vienna_for a limited agreement prov ing quantitative limitations on major offensive ms thus curbing as soon as possible the present 85-9 'ld up in particular and an ARM limitation at as low a level as is negotiable A MIRV ban may not be in US interests unless there is a relatively low ABM level but a low ABM level is in our interests regardless of whether we ban MIRVs if in accepting a low 1evel we buy an 58-9 freeze Apart from the complexities of the MIRV issue and difficulties in reaching decisions on it this is an additional reason for pressing in the first instance on ABM limitations Reasons for Seeking a MIRV Ban and a Low ABM Level In the absEnce of a MIRV ban and low ABM level the US would rapidly move ahead in the early 197033 in offensive capa bility--but in the mid and late 1970's the Soviets would be able to make use of the high MIRV potential of the large missile which has a seven-fold advantage in payload GROUP 1 4 Excluded from automatic downgrading and declassification I - - areas - I j ELDECLASSIFIED I 5 amounts-n AT THE ARCHIVES it ng i-Y - Mh I '5 TOP SECRET capacity over Minuteman Thus despite the US lead in MIRV deployment with no SALT limitation the USSR could have up to 1 700 hard target reentry vehicles RVs out of a total of up to 3 600 RVs by l9 5 and up to 4 600 RVs including 3 300 hard target RVs by the end of the decade The US force is planned to grow to over 7 000 RVs by 1976 and Soviet planners must assume continuing improvements in US accuracies would give them a cross targeting capability against hard tergets Each side will be impelled by these' developments to intensify its own efforts as a hedge against uncertainties which could imperil its strategic deterrent thus driving a spiral of-strategic arms competition Each side would no doubt take actions to reaSSUre that it retained a secure second- strike capability but this would involve a process marked by uncertainties instabilities and high costs with no gain in security On the ABM side the Soviet 64 launcher_MOScow deployment is virtually comnleted but no a ddi tiona deployments have been started We estimate however that in the absence of arms control limitations the Soviets could have up to 2 100 ABM launchers by the end of the decade The full Safeguard deployment is scheduled to be completed by the end of 1977 it is planned to have 879 launchers With no or high limits on ABMs and no MIRV ban the momentum of the arms competition clearly will require major new US strategic programs in this decade beyond those presently projected Moreover this intensified competition will involve strategic instabilities It would be highly desirable to avoid such a situation through arms control banning MIRHs and holding ABMs to a low level Relationship MIRVs serve two roles to increase the numbers of targets hit and or to ensure penetration of ABM defenses ABM seeks to reduce the number of penetrations and targets hit Limitations on the two systems are ineluctably related TOP SECRET - nmonucsn AT THE new mam-Es 1 Rum It 5 5 I By Dale 7 2 funTOP SECRET 1 -3- - Since our cardinal aim is deterrence rather than a first- strike capability we must assure our own retaliatory forces survivability and abiliL ty to penetrate defenses but we do not need to aim beyond that to destroy enemy strategic capabilities If the Soviets have similar basic aims as they said at Helsinki agreement on MIRV and ABM limitations may be possible With zero or very low ABM levels we do not need capabilities to penetrate ballistic missile defenses With high ABM levels either allowed under an agreement or in the absence of an agreement we need MIRVs to assure adequate coverage and penetrability Where the'division between low enough and too high levels rests is not agreed but full Safeguard ABM levels say about 1 000 launchers is generally con- sidered too high to justify the US foregoing MIRVS This' is true not so much because of the density of defensive interceptor missiles but because any nation- wide or widely deployed system requires so many dispersed -arge ABM acquisi tion radars that the r1_sks of clandestine SAM upgrading covert or post-abrogation rapid deployment of relatively short- -lead time ABM interceptors could imperil maintenance of our assured retaliatory penetration The obverse is not true In the absence of a MIRV ban it is still highly desirable to limit ABMs sharply in order to limit Soviet defense and since survivability of our retaliatory force can be better assured by other means than ABM defense e g by constraining Soviet offensive forces by retaining options for ULMS and advanced bombers and by reducing uncertain 5 ties and instabilities To illustrate the point on survivability it is evident that a Soviet hard target force of over 3 000 accurate reentry vehicles by the end of the decade could readily overwhelm a US ABM force much larger than Safeguard defending Minuteman sites A HIRV ban coupled with quantitative reatrictions would greatly reduce this threat though not remove it p entirely due to the accuracy of the 55 9 and the possibility '10 SECRET - 1- REPRODUCED AT THE NATIONAL mowcs all Amway - NARA TOP swam of improving the accuracy of the But the main criterion remains the number of RVs surviving a first- strike which penetrate Soviet defenses it depends' both on the Soviet offensive force and the Soviet defensive force With a MIRV ban and very low ABM levels the US would have a survivable retaliatory capability Iverification and Risks A ban only on deployment of MIRVs could not be adequately verified except perhaps by highly intrusive random on-site inspection of deployed'hibsile warheads which would almost certainly not be negotiable Verification would have to center on monitoring a collateral ban on MIRV developmental and confidence flight testing It w0uld also be necessary in a collateral ban to prohibit flight testing of all multiple reentry vehicles maneuverable reentry vehicles and endo atmospheric penetration aids It would be desirable to limit permitted missile Flight tests to preLannounced firings on agreed ranges in orderLto heighten the effectiveness of our national means of verification - In our view with which Defense takes issue Soviet testing of multiple reentry vehicles has not advanced to a point which would make impractical a MIRV flight test ban Verification of a zero ABM level would be easiest A low limit on ABM deployment could however also be monitored by national means Inclusion of negotiated limitations on ABM associated radars would be an important element in facilitating verification US testing on the other hand has proceeded to the point where we could forego further tests and still deploy designed to penetrate Soviet defenhes with confidence The Soviets may therefore not wish to accept a ban which pre cludes their catching up in the gap This however is a negotiability problem rather than a verification problem at least so far as we are concerned I if TOP SECRET I UEGLAS 51 EU REPRODUCED AT THE M mm m i mommy c11_ By EFL NARA 0331 4432 r TOP SECRET well as an important limitation on over all ABM capability The lower the permitted ABM level and the more geographically compact the deployment the lower the numbers and density of associated ABM radars and hence the less the risks of upgraded or SAMs with marginal ABM capability We believe that if the soviet Union were prepared to agree to a MIRV ban and low ABM levels they probably would not intend to violate the agreement To do so and be caught would involve high political risks and costs Nonetheless we must of course weigh the consequences of cheating however unlikely and the above restrictions have been considered with an to I our capability to veri y soviet compliance Strategic Implications and low ABM limitation would permit us to meet sufficiency criteria in most cases more surely or less expensively than leaving MIRVs uncontrolled and AEMs uncontrolled or limited to Safeguard or other high levels The one exception wouldgbe limiting damage from small or accidental attacks which would not be met or fully met by zero or low ABM lev81s A minimal area defense of the US against accidental or small Chinese attacks could perhaps be met by a nation-wide thin deployment lower than the full Safeguard level but it is not certain even this would curb the density of associated radars sufficiently to provide the high confidence against SAM upgrading that would be desired with a MIRV ban In short it may be necessary not only to choose between a China defense in the 19 0's and low ABM levels but also between a China defense and a MIRV ban Concurrence - Mr Perezf w i cc ' - Mr Okun -f Mr Getz EUR - Mr Hillenbrand INR - Mr Denney - Mr Cargo Mr Neuman Farley Isa RLGarthoff pep TOP 1 94 w- 1 This document is from the holdings of The National Security Archive Suite 701 Gelman Library The George Washington University 2130 H Street NW Washington D C 20037 Phone 202 994-7000 Fax 202 994-7005 nsarchiv@gwu edu