Michael Hayden Armacost (born April 15, 1937)^[1] is a retired American diplomat and a fellow at Stanford University's Freeman Spogli Institute. He was acting United States Secretary of State during the early days of the administration of President George H. W. Bush, before Secretary James Baker was confirmed by the Senate. Armacost also served as United States Ambassador to Japan and the president of the Brookings Institution from 1995 to 2002.

In the 1960s, Armacost taught international relations and foreign policy at Pomona College.^[2]

Armacost was a White House Fellow in 1969-1970. Founded in 1964, the White House Fellowship is one of America’s most prestigious programs for leadership and public service. The Fellowship, awarded on a strictly non-partisan basis, offers exceptional young leaders first-hand experience working at the highest levels of federal government.

In January 1977 Armacost was selected as a member of the National Security Council to handle East Asian and Chinese affairs under the Carter administration until July 1978, when he was replaced by Nicholas Platt. Years later he was appointed to be the United States Ambassador to Japan from 1989 to 1993, Under Secretary of State for Political Affairs from 1984 to 1989, and United States Ambassador to the Philippines from 1982 to 1984, during a critical period of political upheaval during the Ferdinand Marcos presidency.^[3]

He served as Acting Secretary of State from January 20, 1989, to January 25, 1989. Between 1995 and 2002, Armacost served as president of the Brookings Institution.

He has received the President's Distinguished Service Award, the Defense Department's Distinguished Civilian Service Award, and the Secretary of State's Distinguished Services Award.

Armacost is the author of three books, the most recent of which, Friends or Rivals?, was published in 1996 and draws on his tenure as ambassador. He also co-edited, with Daniel Okimoto, The Future of America's Alliances in Northeast Asia, published in 2004 by Stanford Walter H. Shorenstein Asia-Pacific Research Center.^[4] Armacost has served on numerous corporate and nonprofit boards, including TRW, AFLAC, Applied Materials, USEC, Inc., Cargill, Inc, Carleton College, and The Asia Foundation.

Armacost received a Bachelor of Arts in international relations (1958) and an honorary degree^[5] (1989) from Carleton College. He was an international fellow of the School of International and Public Affairs, Columbia University in 1961.^[6] He earned his Ph.D. from Columbia University in 1965.

Armacost is a Fellow of the National Academy of Public Administration.^{[citation needed]} He was chairman of Carleton College's board of trustees from 2004 to 2008.^[7]

• Order of the Rising Sun, Grand Cordon, 2007 (Japan).^[8]