243. National Security Decision Memorandum 1581


  • The Secretary of State
  • The Secretary of Defense
  • The Director, Arms Control and Disarmament Agency
  • The Director of Central Intelligence


  • Instructions for the Strategic Arms Limitation Talks at Helsinki (SALT VII)

After considering the discussions and recommendations of the National Security Council, I have decided on the United States position for presentation at Helsinki (SALT VII).

Offensive Limitations

The Delegation should initially concentrate its efforts on reaching an agreement on offensive limitations. The Delegation must make it clear that our final decision on ABMs will be heavily influenced by the scope of the Interim Agreement.
Accordingly, the Delegation will continue to press for the inclusion of limits on SLBM launchers in the Interim Agreement. The Delegation should propose, at the outset, that the SLBM freeze date start on the date of signature of the Interim Agreement (rather than July 31, 1971).
At a time he deems appropriate, the Chairman of the Delegation should propose that the ICBM launcher construction freeze also start on the date of the signature of the Interim Agreement. In this connection, the proposal that MLBM launchers be limited to those externally completed by December 31, 1971, should be withdrawn.
It is important that the two countries agree, either in the Interim Agreement or in an interpretive statement, that launchers for older, heavy ICBMs (Titans, SS–7s, SS–8s) cannot be converted to accept Modern Large Ballistic Missiles (MLBMs). Regarding other limits on the conversion of launchers to accept MLBMs, the Delegation should propose (a) moving the depth-and-diameter constraint to an agreed interpretive statement, and (b) redefining heavy strategic ballistic missiles as those of a size greater than the SS–11. Subsequently, the Chairman [Page 739] of the Delegation may, if he deems it necessary, drop the proposal for agreement on the depth-and-diameter constraint through an agreed interpretive statement and introduce a unilateral statement that the U.S. would consider changes in silo depth or diameter as indicators of possible non-compliance with the MLBM limitation.
The Delegation should continue efforts to get limitations on land-mobile ICBM launchers and soft-pad ICBM launchers included in the Interim Agreement. In either or both cases, the Chairman of the Delegation may, at his discretion, propose agreed interpretive statements on such limitations in place of specific provisions in the Interim Agreement.
See Annex A for instructions regarding the general definition of ICBMs and limits on test and training launchers.
The Delegation should strongly reaffirm our position regarding duration and withdrawal. (See paragraph 4, NSDM 145.)2 The period now unspecified in the special withdrawal provision proposed by the U.S. should be five years. After further negotiation, the Delegation may recommend alternative positions for Presidential decision; while the terms for continuing the agreement might vary (e.g., fixed duration with automatic renewal or extension by mutual agreement), the minimum duration of the interim agreement, unless replaced by a more complete follow-on agreement, must be five years.

Defensive Limitations

Our formal position on the number of ABM sites and ABM launchers/interceptors remains unchanged.
The Chairman of the Delegation is directed to explore privately with the Chairman of the Soviet Delegation the proposal that, if the Soviets agree to include SLBM launchers in the Interim Agreement, the U.S. will consider changes in our ABM position. He should suggest that the U.S. would be prepared to negotiate an agreement which would take account of the Soviet interest in ICBM defense. If the Soviets show interest in this proposition and press for a more precise statement, the Chairman of the U.S. Delegation is authorized to reply that the U.S. would accept a two-for-two ABM arrangement with 200 ABM launchers/interceptors. (No more than 100 ABM launchers/interceptors are allowed at any one site.) Each country would have the right to either (a) NCA defense plus defense of one ICBM field, or (b) defense of two ICBM fields. The location of the ICBM fields would be subject to the geographical limitations in our present proposal. Moreover, there would be a right to change the location subject to [Page 740] agreed procedures. (These procedures need not be agreed upon prior to any change in location of a deployment area.)
If the Soviets indicate they will accept the inclusion of SLBM launchers in the Interim Agreement, then the Chairman of the Delegation is authorized to make a formal proposal of the two-for-two ABM sites.
If, however, the Soviets continue to reject the inclusion of SLBM launchers in the Interim Agreement after the first three weeks in Helsinki, then the Delegation should make recommendations for Presidential decision regarding the inclusion of SLBMs and ABM levels.
For ABM defense of the national capital, the Chairman of the Delegation is authorized to accept, at his discretion, the 150 kilometer radius proposed by the Soviets. On the other hand, the Delegation should initially hold to our present proposed limit of four Modern ABM Radar Complexes. If he deems it necessary, the Chairman of the Delegation may propose six MARCs.
For ABM defense of ICBM fields, the Delegation should press to get Soviet acceptance of the principle of Modern ABM Radar Complexes (MARCs). The Delegation should initially hold to the limit of four MARCs for two ICBM fields. The Delegation should indicate that there is flexibility in our position on the number of MARCs. If he deems it necessary, the Chairman of the Delegation should propose, at his discretion, up to six MARCs for each ICBM field. (In the case of paragraph 11 where one country chooses NCA defense and one ICBM defense site, the number of allowed MARCs for each ICBM field would be one-half the number of the two ICBM fields.)
Should the formal proposal in paragraph 10 be made and should the Soviets continue to resist the principle of MARCs for ICBM defense, the Chairman of the Delegation should explore how agreement might alternatively be reached with the Soviets on a combination of qualitative and quantitative ABM radar limits. Specifically, with an exception for the four Safeguard radars at our two ICBM defense sites, ABM radars for ICBM defense should not be larger than 106 watt-meters squared. In conjunction with this, the number of ABM radars for ICBM defense sites should be limited so that each party would be assured that neither side would undertake extensive deployments of these radars (i.e., beyond the number which would provide adequate support to the agreed level of ABM launchers/interceptors).
The Delegation should continue for now to press for strict limits on Other Large Phased Array Radars (i.e., our “mutual agreement” proposal or the proposal offered to the Soviets on January 26, 1972).
The Delegation should reaffirm the importance of our provision regarding withdrawal in case the follow-on negotiations fail (i.e., our proposed addition to Article XV of the Joint Draft Text). The [Page 741] period now unspecified in the provisions should be five years. I am prepared to omit this provision. However, before authorizing the Delegation to do so, I ask that the Delegation forward for my approval as soon as possible a scenario whereby the U.S. could affirm that failure to replace the Interim Agreement with more complete limitations on strategic offensive arms could jeopardize our supreme interests and, if so, would constitute a basis for withdrawal from the ABM treaty.
The Chairman of the Delegation should, at a time which he deems appropriate, make a statement along the lines that: If the USSR were to undertake a concerted program which substantially increased the threat to the survivability of our strategic retaliatory forces, the U.S. would consider this to jeopardize our supreme interests. Consequently, this could be a basis for withdrawal from the ABM treaty.

Other Issues

At Annex A is guidance on the other issues relating to the Joint Draft Texts and associated interpretive statements.
The Chairman of the Delegation is authorized to inform the Chairman of the Soviet Delegation that, subject to satisfactory resolution of the issues covered by paragraph 18 above and of the issues reflected in the bracketed portions of the Joint Draft Texts, the unbracketed portions of the Joint Draft Texts would be acceptable to the U.S.
We must be particularly careful to avoid leaks during the next few weeks since the negotiations have entered an especially sensitive stage. To this end, all substantive statements on SALT are to be cleared through the White House.

Richard Nixon

Annex A

On the general definition of ICBMs, the Delegation should continue efforts to get our present proposal accepted or can propose an alternative definition similar to: “ICBMs are any land-based strategic ballistic missiles capable of ranges in excess of the distance between the eastern-most part of the U.S. and the nearest part of the USSR, including those deployed for possible use at lesser ranges.”
Either formulation which the Delegation has proposed for test and training launchers would be acceptable. In this connection, the Delegation should inform the Soviets that the U.S. would view as inconsistent with the Interim Agreement a significant increase in the proposition of test and training launchers for MLBMs.
With regard to each of the issues examined in the Interagency Paper “Issues Arising from Agreed Language in the Joint Draft Texts [Page 742] and from Associated Interpretive Statements,” dated March 6, 1972, the following guidance applies.
ABM Treaty, Article I, 2 (Territorial Defense). This should be retained in its present form.
ABM Treaty, Article IV (Test Ranges). The Delegation should make clear that the 15 launchers is an aggregate limit—e.g., by changing the language in the second sentence of Article IV. Moreover, the Delegation should seek an understanding on what are the current test ranges.
ABM Treaty, Article V, 1 (Mobile ABM components). The Delegation should make it clear to the Soviets that this provision applies to all ABM components (viz., launchers, interceptors, radars, and other devices capable of substituting for them) which are not fixed land-based. The Delegation should seek to revise Article V, 1, along the following lines: “Each party undertakes not to develop, test, or deploy ABM systems or components which are sea-based, air-based, space-based, or mobile land-based.” If the Soviets raise the issue, the Delegation should state that the revised provision does not apply to such devices as satellites providing early warning by detection of missile launch.
ABM Treaty, Article VI (a, b) (Test in an ABM mode). At an appropriate time, the Delegation should provide the Soviet Delegation with qualitative examples, such as those listed in the interagency paper, “Testing in an ABM Mode,” to clarify our interpretation of that phrase.
ABM Treaty, Article VI (b) (Deployment of ballistic missile early warning radars). Final acceptance of this provision should be deferred until the issue of OLPARs is resolved.
ABM Treaty, Interpretive Statement on Multiple Warhead ABMs. The Delegation should seek Soviet agreement to the U.S. interpretation presented on January 28, 1972.
ABM Treaty, Interpretive Statement on Defense of Early Warning Radars. The Delegation need make no further statement on the subject.
ABM Treaty, Interpretive Statement on Technology of Early-Warning Radars. The Delegation need make no further statement.
ABM Treaty, Interpretive Statement on Selective Direct Observation (SDO). The Delegation should not make the earlier proposed statement on SDO.
ABM Treaty and Interim Agreement, Interpretive Statement on Verification. The Delegation should not make the proposed statement on operation of national means of verification.
Interim Agreement, Interpretive Statement on Test and Training Launchers. See paragraph 2 above.
Documentation of Interpretations of SALT Agreements. The Delegation should propose that agreed interpretations or understandings [Page 743] relating to the Agreements should be documented in an agreed summary record, available for public use, to be initialled by the Chairmen of the Delegations or their designees.
  1. Source: National Archives, Nixon Presidential Materials, NSC Files, NSC Institutional Files (H–Files), Box H–208, National Security Decision Memoranda, NSDMs 151–200. Top Secret; Nodis; SALT.
  2. Document 221.