Arthur A. Hartman, a career diplomat who served as President Carter’s ambassador to France and President Reagan’s ambassador to the Soviet Union, where he represented the United States through a tumultuous period of the Cold War, died March 16 at a hospital in Washington. He was 89.

The cause was complications from a fall, said his son David Hartman.

In a diplomatic career spanning four decades, Mr. Hartman held high-ranking posts under Republican and Democratic presidents and developed a reputation, the New York Times once reported, as “one of the brainiest and most professional members of the Foreign Service.”

Under Henry Kissinger, the secretary of state during the Nixon and Ford administrations, Mr. Hartman was assistant secretary of state for European affairs. In 1977, he assumed his ambassadorship in France, where his tenure straddled the centrist government led by President Valéry Giscard d’Estaing and the subsequent Socialist administration of François Mitterrand.

Mr. Hartman made an impression on the French for his conspicuous presence at artistic events such as the opera, leading to a flattering profile in a liberal newspaper catering to the Parisian intelligentsia. “Not since Benjamin Franklin,” the Times noted, “has an American envoy to France been given such public recognition for his culture.”

Arthur A. Hartman IN September 1981. (James K. W. Atherton/The Washington Post)

He moved to Moscow in 1981 and remained there until 1987 — the longest tenure of any U.S. ambassador to the Soviet Union since before World War II and one that spanned the pivotal years from the death of Leonid Brezhnev to the rise of Mikhail Gorbachev.

Mr. Hartman led the embassy during events that included the historic summits attended by Reagan and Gorbachev in Geneva in 1985 and in Reykjavik the following year.

He contended with crises including the downing of Korean Air Lines Flight 007 by the Soviet military in 1983, the Chernobyl nuclear disaster in 1986 and, later that year, the detainment of U.S. journalist Nicholas Daniloff on espionage charges.

His challenges also included what he described as the restrictive character of Soviet society — he said he was never invited to a counterpart’s home or dacha — and the staffing problems created by a diplomatic feud in which the Soviet government barred dozens of Soviet citizens from continuing their employment at the embassy. He acted as his own chauffeur, and his wife, Donna, cooked for visitors so that diplomatic functions could go on.

Mr. Hartman’s time at the embassy encompassed a period of concern about feared security breaches that included the bugging of embassy typewriters and the seduction by Soviet agents of U.S. Marines tasked with guarding the embassy.

Some officials in Washington, including Navy Secretary James H. Webb Jr., alleged that Mr. Hartman had permitted an environment at the embassy that was too lax, and a 1987 commission led by former defense secretary Melvin Laird found that Mr. Hartman had “failed to take appropriate steps to correct the situation.”

Mr. Hartman, who left his post in 1987, characterized that conclusion as “very unfair.” The State Department had defended him earlier as “one of the nation’s distinguished career diplomats whose years of service have been a model of dedication to the national interest.”

In 1988, The Washington Post reported that “no evidence” had been uncovered “to confirm that the KGB penetrated the Moscow Embassy.”

Jack F. Matlock Jr., who followed Mr. Hartman as U.S. ambassador in Moscow, said in an interview that his predecessor “did a marvelous job” under difficult circumstances. He credited Mr. Hartman and his wife with cultivating cultural contacts in the Soviet Union, particularly with dissident artists.

The Hartmans welcomed Vladimir Horowitz, the acclaimed Russian-born pianist, when he returned to his homeland in 1986 for the first time in six decades.

Arthur Adair Hartman was born March 12, 1926, in New York City. He served in the Army Air Forces during World War II before receiving a bachelor’s degree from Harvard University in 1947.

In the early years of his career, he worked in Europe helping administer the Marshall Plan and rose through the Foreign Service in part through his relationships with influential undersecretaries of state George W. Ball, Nicholas deB. Katzenbach and Elliot L. Richardson.

Mr. Hartman served as economic officer in Saigon and head of the London embassy’s economic section, among other assignments. After retiring from the Foreign Service, he was a consultant with Apco Associates.

Survivors include his wife of 66 years, the former Donna Ford, of Washington; five children, David Hartman of Rochester, Mich., John Hartman of Vero Beach, Fla., Sarah Hartman of Brooklyn, J. Lise Hartman of Paris and Benjamin Hartman of Manhattan; 15 grandchildren; and seven great-grandchildren.

Among the dissident artists Mr. Hartman aided was pianist Vladimir Feltsman. The ambassador organized several concerts for him at the Spaso House, the envoy’s official residence, when Feltsman was not permitted to play elsewhere in his country. Before one of the recitals, the strings of the ambassador’s piano were mysteriously cut.

Feltsman credited Mr. Hartman with helping him obtain the visa that allowed him to come to the United States in 1987.

“None of us thought, when we were sitting around keeping up one another’s morale in Moscow, that this would ever happen,” Mr. Hartman said on the occasion of the pianist’s first concert in the United States — at the White House. “But it has.”