Kissinger, 91, underwent an aortic valve replacement procedure, according to NewYork-Presbyterian Hospital. The German-born Jewish refugee served as Secretary of State under Republican Presidents Richard Nixon and Gerald Ford, with a hand in the diplomatic opening of China, landmark US-Soviet arms control talks, expanded ties between Israel and its Arab neighbors and the Paris Peace Accord with North Vietnam.
While many hailed Kissinger for his brilliance and broad experience, some opponents branded him a war criminal for his support for anti-communist dictatorships, especially in Latin America.
Following the Paris Peace Accords reached in January 1973, Kissinger shared a controversial Nobel Peace Prize with North Vietnam's Le Duc Tho.
After leaving government, Kissinger set up a high-powered consulting firm in New York. He also has served on corporate boards and various foreign policy and security forums, written books and served as a media
commentator on international affairs.
(Reporting by Ellen Wulfhorst in New York and Bill Trott in Washington; Editing by Eric Walsh)