The United States and South Korea (Republic of Korea, or ROK) signed the Mutual Defense Treaty on October 1, 1953, and it went into force in 1954. The United States agreed to defend South Korea against future attacks by North Korea.
The Parties to this Treaty,
Reaffirming their desire to live in peace with all peoples and an governments, and desiring to strengthen the fabric of peace in the Pacific area,
Desiring to declare publicly and formally their common determination to defend themselves against external armed attack so that no potential aggressor could be under the illusion that either of them stands alone in the Pacific area,
Desiring further to strengthen their efforts for collective defense for the preservation of peace and security pending the development of a more comprehensive and effective system of regional security in the Pacific area,
Have agreed as follows:
The Parties undertake to settle any international disputes in which they may be involved by peaceful means in such a manner that international peace and security and justice are not endangered and to refrain in their international relations from the threat or use of force in any manner inconsistent with the Purposes of the United Nations, or obligations assumed by any Party toward the United Nations.
The Parties will consult together whenever, in the opinion of either of them, the political independence or security of either of the Parties is threatened by external armed attack. Separately and jointly, by self help and mutual aid, the Parties will maintain and develop appropriate means to deter armed attack and will take suitable measures in consultation and agreement to implement this Treaty and to further its purposes.
Each Party recognizes that an armed attack in the Pacific area on either of the Parties in territories now under their respective administrative control, or hereafter recognized by one of the Parties as lawfully brought under the administrative control of the other, would be dangerous to its own peace and safety and declares that it would act to meet the common danger in accordance with its constitutional processes.
The Republic of Korea grants, and the United States of America accepts, the right to dispose United States land, air and sea forces in and about the territory of the Republic of Korea as determined by mutual agreement.
This Treaty shall be ratified by the United States of America and the Republic of Korea in accordance with their respective constitutional processes and will come into force when instruments of ratification thereof have been exchanged by them at Washington.(2)
This Treaty shall remain in force indefinitely. Either Party may terminate it one year after notice has been given to the other Party.
IN WITNESS WHEREOF the undersigned Plenipotentiaries have signed this Treaty.
DONE in duplicate at Washington, in the English and Korean languages, this first day of October 1953.
UNDERSTANDING OF THE UNITED STATES
[The United States Senate gave its advice and consent to the ratification of the treaty subject to the following understanding:]
It is the understanding of the United States that neither party is obligated, under Article III of the above Treaty, to come to the aid of the other except in case of an external armed attack against such party; nor shall anything in the present Treaty be construed as requiring the United States to give assistance to Korea except in the event of an armed attack against territory which has been recognized by the United States as lawfully brought under the administrative control of the Republic of Korea.
[The United States communicated the text of the understanding to the Republic of Korea in a note of January 28, 1954, acknowledged by the Republic of Korea in a note of February 1, 1954. The text of the understanding was included in the President's proclamation of November 17, 1954.]
(1) TIAS 3097, 5 UST 23602376. Ratification advised by the Senate Jan. 26, 1954, and ratified by the President Feb. 5, 1954, subject to an understanding; entered into force Nov. 17, 1954.
(2) Ratifications were exchanged Nov. 17, 1954.