Question: Before being the United States Secretary of State who did Dean Rusk send official diplomatic correspondence too?

Context paragraphs:
United States Ambassador to Sweden: The United States Ambassador to Sweden (Swedish: "USA:s ambassadör i Sverige" ) serves as the official diplomatic representative of the President and the Government of the United States of America to the King and the Government of the Kingdom of Sweden.  Diplomatic relations between Sweden and the United States began with the signing of the Treaty of Amity and Commerce in 1783.

Rusk documents: The Rusk documents (also known as the Rusk–Yang correspondence) are the official diplomatic correspondence sent by Dean Rusk, the United States Assistant Secretary of State for Far Eastern Affairs, to Yang You Chan (양유찬, 梁裕燦), the South Korean ambassador to the U.S at the August 10, 1951.

Russia–Vanuatu relations: The Republic of Vanuatu and the Union of Soviet Socialist Republics established official diplomatic relations on June 30, 1986 - three months to the day before Vanuatu established diplomatic relations with the United States.  The USSR broke up and Russia emerged as its successor state in 1991.

David Rusk: David Patrick Rusk (born c. 1940) is an American politician.  He served as mayor of Albuquerque, New Mexico from 1977 to 1981.  He is the son of former United States Secretary of State Dean Rusk.  Rusk is an alumnus of the University of California, Berkeley.

Rusk County Historical Society Museum: The Rusk County Historical Society Museum is a museum in Ladysmith, Wisconsin, United States.  The museum contains over 9,000 artifacts relating to the history of Rusk County.  The Rusk County Historical Society was incorporated in 1955 and is a non-profit organization.  The historical society has a museum that is located at the Rusk County Fairgrounds in Ladysmith, WI.  The museum is open from 12:30-4:30 on weekends Memorial Day through Labor Day.  The objectives of the society are the discovery, preservation, and public dissemination of the history of Rusk County and the State of Wisconsin.

Dean Rusk: David Dean Rusk (February 9, 1909December 20, 1994) was the United States Secretary of State from 1961 to 1969 under presidents John F. Kennedy and Lyndon B. Johnson.  Rusk is one of the longest serving U.S. Secretaries of State, behind only Cordell Hull.

List of diplomatic missions in the United States: This is a list of diplomatic missions in the United States.  At present, 177 nations maintain diplomatic missions to the United States in the capital, Washington, D.C. Eight nations also attribute their missions at the United Nations in New York as their official embassies to the United States.  However, only those offices in New York that serve as an official diplomatic mission to the United States are listed here.  For a complete list of diplomatic missions to the United Nations, see List of current Permanent Representatives to the United Nations.

UC Berkeley School of Law: The University of California, Berkeley, School of Law, commonly referred to as Berkeley Law and Boalt Hall, is one of 14 schools and colleges at the University of California, Berkeley.  Berkeley Law is consistently ranked as one of the top law schools in the nation.  The law school has produced leaders in law, government, and society, including Chief Justice of the United States Earl Warren, Secretary of State of the United States Dean Rusk, Attorney General of the United States Edwin Meese, United States Secretary of the Treasury and Chairman of the Federal Reserve G. William Miller, Solicitor General of the United States Theodore Olson, and lead litigator of the "Korematsu v. United States" civil rights case, Dale Minami.

Palestine–United States relations: Palestine – United States relations are relations between the State of Palestine and the United States.  Official diplomatic relations do not exist in the sense of diplomatic exchanges and consular services since the United States does not recognize Palestine as a state.

Israel–United Arab Emirates relations: Israel – United Arab Emirates relations do not currently exist.  The United Arab Emirates does not recognize Israel as a state and the two countries do not have diplomatic or economic relations.  Israel in 2015 opened an official diplomatic mission in Abu Dhabi to the International Renewable Energy Agency.

Supporting paragraphs: Rusk documents Dean Rusk
Answer: Yang You Chan