223. Memorandum From Philip Odeen of the National Security Council Staff to the President’s Assistant for National Security Affairs (Kissinger)1


  • Modernization of the UK SLBM Force

I hear rumors to the effect that the British have reached a tentative decision to forego Poseidon and instead pursue their Super Antelope Polaris upgrade program. A Cabinet meeting is reportedly scheduled [Page 720] for early next week to reach the final decision. The British will inform us of this decision within the next few days and a request for U.S. assistance in Super Antelope will be forthcoming.

I have reviewed the information available to me on the negotiations (much of it handled by Jim Schlesinger) that led up to the decision. As I understand the background, a critical ground rule from the outset was that the U.S. would not sell the fully MIRVed Poseidon to the UK. I suspect that the decision not to sell MIRV played an important role in influencing the British to choose the less capable Super Antelope system. In the long run, this will reduce the capability and credibility of the British deterrent.


The U.S. concluded in the mid 1960s that small, multiple RVs were a superior method of penetrating ABM defenses. Multiple RVs are insensitive to minor changes in the threat of the type which had been the bane of U.S. penetration aid programs. Thus Schlesinger and others who looked at the British penetration problem concluded that Poseidon with its small multiple RVs offered the highest confidence answer and was a logical choice. Moreover, Poseidon provides an increase in submarine operating area and hence improved survivability over Polaris. Super Antelope on the other hand decreases Polaris range cutting the available operating area in half. These conclusions were shared by the British but they also had to contend with strong internal governmental pressure in favor of Super Antelope, the anticipated high cost of acquiring Poseidon, and other considerations.

The cost problem was seriously and unknowingly compounded by the U.S. decision that we would not sell the MIRVed Poseidon to the UK. Schlesinger proposed the option of a “de-MIRVed” Poseidon. This was intended to give the British the desired penetration capability without raising the political problems perceived in transferring MIRVs.

Because he was operating under tight secrecy restrictions, Schlesinger involved only a handful of people in his studies and negotiations with the UK. It was assumed by Schlesinger and his small staff that Poseidon could credibly be “de-MIRVed” at slight additional cost. Schlesinger provided the UK with an estimate for procurement of de-MIRVed Poseidon of $500–620 million, but Schlesinger added “plan on $700 million.”

The British were frankly skeptical of Schlesinger’s estimate and the U.S. had little back-up data to support it. The British, though they did not have access to all the needed technical information on Poseidon, generated their own estimate of about $1 billion to buy Poseidon in the de-MIRVed configuration. This is about twice the estimated cost of Poseidon with MIRV.

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My own brief investigation into the matter suggests the British estimate is much closer to the mark than Schlesinger’s. In denying MIRV to the British we effectively doubled the price they perceived they would have to pay to buy the high confidence penetration of Poseidon.

In May, you visited London after your Moscow trip. You told the UK that SALT and the Soviets should not impinge on the British options. We followed that up with a paper you gave to Cromer which reiterated that point.

As a result of these discussions, the British thought you were indicating that we would consider selling Poseidon with MIRV. They may have latched onto this idea because they were increasingly concerned about the added cost and feasibility of “de-MIRVing” Poseidon. Trend’s June note to you asked for clarification on this point as, in his words: “If the President were ready to contemplate the possibility of offering the fully MIRVed Poseidon there would, as you will recognize, be substantial advantages for us which we should wish to have the opportunity of weighing up before finally making our choice of options.”

The U.S. reply was that the British “should only consider the range of upgrade options offered in our past discussions,” i.e., no MIRV capability. After our reply was transmitted to the British I heard that London now viewed things in a different light.

My Assessment

From the standpoint of military effectiveness and strengthening the British deterrent, there is no question that Poseidon is the preferred answer for the British as it is for the U.S.

Super Antelope, which the British have chosen, relies on decoys for penetration and is a technically complex and challenging undertaking. In fact, the U.S. technical evaluation has called its very feasibility into question.

Trend’s note clearly implied a UK interest in buying Poseidon with MIRV. In turning them down we have unwittingly doubled the price they face from $500 million for Poseidon with MIRV to $1 billion for Poseidon without MIRV. This, in turn, may have been an important influence in causing them to fall back to the less capable Super Antelope.

While it is possible that other considerations swayed the UK to choose Super Antelope (e.g., prospects for future cooperation with France, internal “buy British” economic and political pressures), it may also be that by refusing to sell them MIRV we have priced them out of the market, forcing them to fall back on a more limited and less capable option.

If the latter is true, we should seriously reconsider the MIRV question. Circumstances, particularly at SALT have changed sufficiently since early this year to warrant re-examination on this issue.

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Next Steps

There is certainly a risk that telling the British we will now sell them MIRVed Poseidon will precipitate problems in our relations and their Ministers may be reluctant to reconsider the question. On the other hand, our long term interests lie with supporting the British deterrent with the best support and advice available and we would be remiss if we failed them on this point.

If you agree that we should reconsider the MIRV issue, you should urgently contact Cromer and pass to Burke Trend the message that we will reconsider the MIRV question if they so request. A draft note for Trend is at Tab A.


That you call Cromer and pass him the note for Trend at Tab A.

  1. Summary: Odeen discussed the modernization of the UK SLBM force.

    Source: National Archives, Nixon Presidential Materials, NSC Files, Kissinger Office Files, Box 63, Country Files, Europe, General, Exchange with the UK—SLBMs (2 of 2). Top Secret; Sensitive; Completely Outside the System. Sent for action. Attached but not published is Tab A. In a July 26 note to Kissinger, Sonnenfeldt wrote, “With the exchange with Heath now underway on Year of Europe and Trend coming over, I don’t see how the message Phil suggests can now be sent.” In an undated note to Kissinger, Scowcroft agreed with Sonnenfeldt and suggested talking to “Schlesinger, on whom we have depended for all our technical data and guidance.” (Ibid.) Kissinger clarified the U.S. position on the MIRVed Poseidon in a July 30 talk with Trend; see Document 27. Memoranda of conversation on Kissinger’s May 10 talks with UK officials are in National Archives, Nixon Presidential Materials, NSC Files, Kissinger Office Files, Box 62, Country Files, Europe, General, UK Memcons HAK London Trip (originals), May 1973.