Initially a liberal Democrat, Kirkpatrick championed human rights, opposed Soviet Union communism and supported Israel.

“She defended the cause of freedom at a pivotal time in world history,” President Bush said Friday. “Jeane’s powerful intellect helped America win the Cold War.”

Secretary of State Condoleezza Rice called her a role model, “an academic who brought great intellectual power to her work.”

Kirkpatrick’s son, Stuart, said she died Thursday at her home in Bethesda, Md. The cause of death was not immediately known. U.N. Ambassador John R. Bolton asked for a moment of silence for her at a meeting of the U.S. delegation to the U.N. in New York.

U.N. Secretary-General Kofi Annan praised “her commitment to an effective United Nations” and said Kirkpatrick was “always ardent and often provocative.”

Kirkpatrick’s health had been in decline recently, her assistant, Andrea Harrington said, adding she had been going to work about once a week “and then less and less.”

The tributes came pouring in:

“America has lost one of its pre-eminent statesmen,” said Sen. Chuck Hagel (news, bio, voting record), R-Neb.

“America has lost a clarion voice for freedom,” said Sen. Joseph Lieberman, D-Conn.

Kirkpatrick is survived by two sons, Stuart and John. Her husband of 40 years, Evron, died in 1995.