226. Memorandum From Secretary of State Rusk to President Johnson1


  • US Adherence to Protocol to Treaty Creating Latin American Nuclear Free Zone
In my memorandum to you of October 25, 1967 (Enclosure A), I recommended that you inform President Diaz of Mexico that the United States intends to sign Protocol II to the Treaty for the Prohibition of Nuclear Weapons in Latin America (Enclosure B).2 This Treaty, which has been signed by 21 Latin American countries and ratified by Mexico [Page 550] and Brazil, would prohibit Latin American Parties from producing, testing, or possessing nuclear weapons in their respective territories; it would also forbid the receipt or installation of any nuclear weapons in such territories. In addition, Latin American Parties to the Treaty would undertake to use nuclear material and facilities under their jurisdiction exclusively for peaceful purposes. The Treaty contains two protocols which are open for signature by the United States.
Protocol I calls for countries outside the Treaty zone to undertake the obligations of the Treaty with respect to their territories within the zone. US adherence to this Protocol would result, for example, in the incorporation of Puerto Rico and the Virgin Islands in the zone. On December 10, 1965, Bill Foster wrote the Chairman of the Negotiating Committee of the Preparatory Commission for the Denuclearization of Latin America that:

“We do not wish to have included in the proposed nuclear free zone the Virgin Islands, since it is United States territory, or the Commonwealth of Puerto Rico, because of its integral relationship with the United States. In the case of both of these areas, the United States must deal with disarmament policies affecting other nuclear powers …”

Protocol II calls upon nuclear-weapon states to agree to respect the obligations set forth in the Treaty and to promise not to use or threaten to use nuclear weapons against Contracting Parties to the Treaty.
On October 26, 1967, you informed President Diaz3 that the United States intends to sign Protocol II with an interpretive statement after consultations with the Congress (Enclosure C). These consultations, necessary because ratification of Protocol II will require the advice and consent of the Senate, are now complete. Both the Joint Committee on Atomic Energy and the Foreign Relations Committee have been briefed in executive session on the Treaty and on our plan to sign Protocol II. Except for Senator Curtis who questioned the reference to general and complete disarmament in the preamble (a similar reference appears in the preamble of the Limited Test Ban Treaty) no objections were raised. At Senator Fulbright’s request, a personal call was made to Senator Hickenlooper who had been present at the Joint Committee but not at the Foreign Relations meeting. Senator Hickenlooper, without committing himself, indicated that, on balance, he would not object to signature of Protocol II with a statement of interpretation, but that he thought ratification should depend on the degree of acceptance of the statement of interpretation [Page 551] by Latin American countries. In addition, Senator Dirksen, the members of the House Foreign Affairs Committee, and the staff of the Preparedness Investigating Subcommittee have been advised that we are giving sympathetic consideration to signing Protocol II. No objections have been expressed.
As indicated in my memorandum to you of October 25 (Enclosure A), I believe that, by adhering to Protocol II, the US would not only be identified with a major arms control measure of special significance to our hemisphere relations, but would also be in a better position to influence the implementation of the Treaty in a manner favorable to our interests. The interpretive statement (Enclosure D) which I would recommend to accompany signature is designed to resolve five matters of concern to the United States. The statement would: 1) make clear that ratification of Protocol II would not constitute United States acceptance of the territorial claims of Latin American Parties; 2) emphasize that the Treaty and its Protocols have no effect upon our transit rights in Latin America; 3) explain our pledge in Protocol II “not to use or threaten to use nuclear weapons against Contracting Parties” so as to permit a nuclear response in the event of an armed attack by a Latin American Contracting Party in which it is assisted by a nuclear-weapon state; 4) reiterate the position of the United States that this Treaty prohibits Contracting Parties from acquiring nuclear explosive devices even if intended for peaceful purposes, but permits the United States to carry out nuclear explosions for peaceful purposes for the Contracting Parties; and 5) state that the United States would act in the same manner with respect to the Latin American territories of Protocol I adherents as it would with respect to the territories of the Contracting Parties to the Treaty, thereby encouraging the Netherlands,4 France, and the United Kingdom5 to ratify Protocol I and providing additional evidence of our support for the proposes of the Treaty at negligible cost. Our “interpretations” would not constitute “reservations” which are prohibited by the Treaty and they would serve to offset interpretations which differ from our own. (For example, the dominant Latin American view, with which we concur, that Contracting Parties cannot acquire nuclear explosive devices for peaceful purposes is not shared by Brazil and Argentina.)
The Latin American countries are observing US actions on Protocol II closely as an indication of our support for the Latin American Nuclear Free Zone and arms control measures generally. An early public announcement, prior to signature of the Protocol, would be highly desirable [Page 552] in order to encourage ratification of the Treaty by additional Latin American nations and to obtain their support in the NPT negotiations.


The United States should not sign Protocol I at this time because of security requirements.
The United States should sign Protocol II as soon as possible, accompanying signature with the interpretive statement set forth in Enclosure D.
You should publicly announce at an early date that the United States is prepared to sign Protocol II.

These recommendations are concurred in by the Director of the Arms Control and Disarmament Agency, the Joint Chiefs of Staff, the Deputy Secretary of Defense and the Atomic Energy Commission.

Dean Rusk 6

Enclosure A7



  • Latin American Nuclear Free Zone Treaty

I believe the President of Mexico will ask you whether the United States is prepared to sign Protocol II to the Latin American Nuclear Free Zone Treaty, better known as the “Treaty of Tlatelolco.” I recommend that you tell him that the United States intends to sign Protocol II.

Signing Protocol II with appropriate interpretative statements is in our view the best way of protecting our transit rights in Latin America for ships and aircraft with nuclear weapons. We believe that the most satisfactory method of achieving an effective interpretation on transit rights is to accompany our signature to Protocol II with an interpretative statement [Page 553] which would be circulated routinely to all signatories, including the 20 Latin American nations which have already signed. We may also wish to inform certain Latin American Governments in advance of the interpretative statements we would plan to make accompanying our signature of Protocol II. We believe the negotiating history of the Treaty makes it clear that our interpretation is the correct one, but we want to do what we can to assure that this interpretation is not contested by important Latin American Governments.

By signing Protocol II, we would agree first, to respect the status of denuclearization of Latin America and second, not to use or threaten to use nuclear weapons on the territory of Contracting Parties. The second obligation would limit to some extent our flexibility of response with nuclear weapons in Latin America. However, we do not believe this limitation to be unreasonable in light of the agreement of the Contracting Parties not to acquire nuclear weapons. With an interpretative statement, we believe the United States’ interests will be protected. The circumstances present in Latin America are such as to justify a departure from our past policy concerning limitations on our freedom of response with nuclear weapons.

There are three other questions which would be dealt with in an interpretative statement to be made at the time of signature. These would be designed to make clear our views on peaceful nuclear explosive devices, on the territorial extent of our Protocol II obligations, and on a definition of territory as it applies to sea and air space. An interpretative statement is not being worked out within the Government and need not be discussed with President Diaz at this time.


That, if asked by the President of Mexico, you might reply along the following lines: “I congratulate you, Mr. President, on an achievement of which your Government can be justly proud. This is the signature by 20 Latin America governments of the first treaty establishing a nuclear free zone. The American people join with me in saluting this unique achievement. We hope this treaty will be a milestone toward world-wide agreement to a non-proliferation treaty and further steps of disarmament. We have followed your efforts with great expectation and have given careful thought and much study to the treaty. We intend to provide you and the other Contracting Parties with a statement of our understanding of the scope and effect of the treaty, and on this basis we intend to sign Protocol II.”
That, if you are asked when the United States will sign, you might state: “I am as anxious as you are to move forward on this important treaty as promptly as possible.”
That, preferably, no public announcement be made of our intention to sign Protocol II at this time since we are not yet actually ready to sign it. If the subject of Protocol II is discussed privately, the communique should read: “The two Presidents discussed the nuclear free zone treaty. President Johnson congratulated President Diaz on this outstanding example of Latin American statesmanship and stated that we are giving our most sympathetic consideration to signing Protocol II.”
That, if you are asked whether we will sign Protocol I, you might state: “Our serious difficulties with Protocol I have already been made known to your Government.” (FYI—the United States cannot sign Protocol I because to do so would require denuclearization of our territories in Latin America, including Puerto Rico. End FYI)

These recommendations are concurred in by the Director of the Arms Control and Disarmament Agency, the Joint Chiefs of Staff and by Assistant Secretary of Defense Paul Warnke.

Dean Rusk 8

Enclosure C9


  • Mr. Ben Read
  • Executive Secretary
  • Department of State—S/S


  • Latin American Nuclear Free Zone

In his conversation with President Diaz Ordaz, the President told him that we intend to sign Protocol II to the Latin American Nuclear Free Zone Treaty with an interpretive statement after consultations with the Congress.

State and ACDA are authorized to proceed with consultations. The results of the consultations should be reported to the President, together with recommendations for the handling of the announcement.

[Page 555]

Enclosure D10


“In signing Protocol II of the Treaty of Tlatelolco, the United States Government wishes to make the following statement:


“The United States understands that the Treaty and its Protocols have no effect upon the international status of territorial claims.

“The United States takes note of the Preparatory Commission’s interpretation of the Treaty, as set forth in the Final Act, that, governed by the principles and rules of international law, each of the Contracting Parties retains exclusive power and legal competence, unaffected by the terms of the Treaty, to grant or deny non-Contracting Parties transit and transport privileges.

“As regards the undertaking in Article 3 of Protocol II not to use or threaten to use nuclear weapons against the Contracting Parties, the United States would have to consider that an armed attack by a Contracting Party, in which it was assisted by a nuclear-weapon State, would be incompatible with the Contracting Party’s corresponding obligations under Article 1 of the Treaty.


“The United States wished to point out again the fact that the technology of making nuclear explosive devices for peaceful purposes is indistinguishable from the technology of making nuclear weapons and the fact that nuclear weapons and nuclear explosive devices for peaceful purposes are both capable of releasing nuclear energy in an uncontrolled manner and have the common group of characteristics of large amounts of energy generated instantaneously from a compact source. Therefore we understand the definition contained in Article 5 as necessarily encompassing all nuclear explosive devices. It is our understanding that Articles 1 and 5 restrict accordingly the activities of the Contracting Parties under paragraph 1 of Article 18.

“The United States further notes that paragraph 4 of Article 18 of the Treaty permits, and that United States adherence to Protocol II will not [Page 556] prevent, collaboration by the United States with Contracting Parties for the purpose of carrying out explosions of nuclear devices for peaceful purposes in a manner consistent with our policy of not contributing to the proliferation of nuclear weapons capabilities. In this connection, the United States reaffirms its willingness to make available nuclear explosion services for peaceful purposes on a non-discriminatory basis under appropriate international arrangements and to join other nuclear-weapon states in a commitment to do so.


“The United States also wishes to state that, although not required by Protocol II, it will act with respect to such territories of Protocol I adherents as are within the geographical area defined in Article 4, Section 2 of the Treaty in the same manner as Protocol II requires it to act with respect to the territories of Contracting Parties.”

  1. Source: Washington National Records Center, RG 383, ACDA/D Files: FRC 77 A 52, Memoranda to the Secretary of State, 1968. Secret. The source text was submitted under cover of an undated memorandum from Fisher to Secretary Rusk, which enclosed for Rusk’s approval “a self-explanatory Memorandum to the President recommending that the United States sign Protocol II to the Latin American Nuclear Free Zone Treaty with an interpretive statement.”
  2. Enclosure B, entitled “Text of LANFZ Treaty” is not attached. For text of Protocol II, see 22 UST 754. The United States is not a signatory to the Treaty for the Prohibition of Nuclear Weapons (Treaty of Tlatelolco) which was signed by 14 Latin American nations at Mexico City on February 14, 1967. Vice President Humphrey signed Protocol II to this Treaty on behalf of the United States at Mexico City on April 1, 1968.
  3. At the invitation of President Johnson, President Diaz of Mexico made a State visit to the United States October 26-28. For text of the joint communique issued by Diaz and Johnson on October 27 following private discussions, and for other remarks issued by both during this visit, see Public Papers of the Presidents of the United States: Lyndon B. Johnson, 1967, Book II, pp. 945-962.
  4. The Dutch have expressed concern to us that Protocol II does not expressly apply to their Latin American territories. [Footnote in the source text.]
  5. The United Kingdom signed Protocols I and II on December 20, 1967. [Footnote in the source text.]
  6. Printed from a copy that indicates Rusk signed the original.
  7. Secret.
  8. Printed from a copy that bears this typed signature.
  9. Confidential.
  10. Secret.