WASHINGTON - Richard Holbrooke, 69, a global troubleshooter for the United States who took on such thorny issues as ethnic warring in the former Yugoslavia, the start of diplomatic relations with China, and, most recently, managing the Obama administration's engagement with Afghanistan and Pakistan, died Monday evening.

Mr. Holbrooke fell ill Friday while working at State Department headquarters and had undergone extensive surgery at George Washington University Hospital for a tear in his aorta.

"One of his friends and admirers once said that, 'If you're not on the team and you're in his way, God help you,' " President Obama said in a statement. "Like so many presidents before me, I am grateful that Richard Holbrooke was on my team, as are the American people."

Secretary of State Hillary Rodham Clinton said Mr. Holbrooke "helped shape our history, manage our perilous present, and secure our future." She called him "the consummate diplomat, able to stare down dictators and stand up for America's interests."

Under four Democratic presidents, from Lyndon Johnson to Obama, Mr. Holbrooke worked on some of the most important diplomatic matters of his era, starting with Vietnam in the Johnson White House. He was renowned for his vast intellect, an ego to match, and an arsenal of weapons ranging from flattery and patience to anger and, when necessary, shouting.

Mr. Holbrooke was probably best known for his work as President Bill Clinton's special mediator to end the war in Bosnia, which culminated in a 20-day negotiating session in 1995 at Wright-Patterson Air Force Base in Dayton, Ohio. The resulting Dayton Peace Accords divided Bosnia into a Muslim-Croat Federation and a Serbian Republic.

In To End a War, his 1998 memoir, Mr. Holbrooke said the U.S. and other nations were late to respond to atrocities by Bosnia's Serbs because of a misguided sense that no outsider could resolve the hatred among Bosnians, Serbs, and Croats.

"Yugoslavia's tragedy was not foreordained," he wrote. "It was the product of bad, even criminal, political leaders who encouraged ethnic confrontation for personal, political, and financial gain."

In 1998, Mr. Holbrooke accepted the challenge of mediating another conflict in the Balkans, the war in Kosovo. Negotiating with Yugoslav President Slobodan Milosevic - the Serb nationalist who died behind bars in 2006 while facing charges of crimes against humanity - Mr. Holbrooke helped win a cease-fire accord that averted a NATO attack on Belgrade, though only temporarily.

When further peace talks failed five months later, NATO launched 78 days of air strikes that ultimately pressured Milosevic to withdraw troops from Kosovo.

Tension and occasional violence continued in the Balkans after Mr. Holbrooke's involvement. In 2008, Kosovo declared independence from Serbia. Mr. Holbrooke and Paddy Ashdown, the European Union's special representative in Bosnia and Herzegovina, warned in October 2008 that Bosnia was again "in real danger of collapse."

Mr. Holbrooke was a denizen of Wall Street and the nonprofit community during Republican George W. Bush's eight years as president. He was vice chairman of Perseus L.L.C., a private-equity firm, and chaired the Asia Society, the American Academy in Berlin, and the Global Business Coalition on HIV/AIDS, Tuberculosis and Malaria.

He was a foreign-policy adviser to Hillary Clinton from her Senate days through her 2008 campaign against Obama for the Democratic presidential nomination.

Days after becoming president in January 2009, Obama named Mr. Holbrooke as special representative for Afghanistan and Pakistan. Mr. Holbrooke spent the last two years visiting those two nations and seeking support from allies to help promote economic development.

James Hoge, a friend and longtime editor of Foreign Affairs magazine, said Mr. Holbrooke "accepted the most difficult assignments, often at great personal cost. He was an inspiring leader to those who worked closely with him."

Richard Charles Albert Holbrooke was born April 24, 1941, in New York City, the first of two sons of Dan Holbrooke, a doctor, and Trudi Moos, the daughter of a leather exporter in Germany, according to a 1998 New York Times profile. Both his parents, as Jews, fled the Nazis in the 1930s.

He graduated from Brown University. He joined the U.S. Foreign Service in 1962, learned Vietnamese, and was sent to Vietnam, where he represented the Agency for International Development in the Mekong Delta, then worked as staff assistant to U.S. Ambassadors Maxwell Taylor and Henry Cabot Lodge.

At the Johnson White House, he wrote one volume of what became known as the Pentagon Papers, the secret history of U.S. involvement in Vietnam that later would be leaked to the Times. In 1968, he was part of the U.S. delegation in Paris, led by W. Averell Harriman, that opened negotiations with North Vietnam.

As assistant secretary of state for East Asian and Pacific affairs under President Jimmy Carter, Mr. Holbrooke was in charge of relations with China when diplomatic ties were normalized in 1978. In a 2008 column, he recalled that he and others in the Carter administration "managed to keep our intense negotiations completely secret" for two years leading to the accord.

President Clinton named him U.S. ambassador to Germany, then assistant secretary of state for Europe, then ambassador to the U.N. At the U.N., Mr. Holbrooke persuaded other countries to recognize AIDS as a national-security issue. In between his government posts, he worked as Peace Corps director in Morocco, editor of Foreign Policy, vice chairman of Credit Suisse First Boston, and managing director of Lehman Brothers.

His first two marriages ended in divorce. Survivors include his third wife, journalist Kati Marton, whom he married in 1995, and two sons.