Alan D. Romberg, an Asia affairs specialist at the State Department who spent more than two decades in the Foreign Service and counseled a generation of China hands, died March 27 at his home in Bethesda, Md. He was 79.

The cause was renal cancer, said a son, Jon Romberg.

Mr. Romberg worked behind the diplomatic scenes to maintain good U.S. relations with China. As a member of the State Department policy planning office in the mid-1990s, he helped repair ties that had been strained by the 1989 Chinese crackdown on Tiananmen Square demonstrators.

“He was centrally involved in negotiations with the Chinese in 1997-1998 to plan the exchange of visits by U.S. President Bill Clinton and Chinese President Jiang Zemin that restored normalcy to U.S.-China relations eight years after the Tiananmen massacre,” Jeffrey A. Bader, who was the National Security Council’s senior director for Asian affairs under President Obama, wrote in an email.

Mr. Romberg also was one of the leading U.S. authorities on the special status of Taiwan, which the United States treated as a self-governing island even as Beijing insisted that it should be recognized as an integral part of China. It was, Mr. Romberg later wrote, a “sensitive triangular relationship” and parsing words was crucial to keeping the Taiwan issue from upsetting ties between Beijing and Washington.

“There are few more complicated or more important aspects of U.S. diplomacy than Washington’s widely misunderstood ‘one-China policy,’ the guiding set of principles behind America’s relationship with both Taiwan and mainland China,” said Thomas J. Christensen, an international relations scholar at Princeton University who served as deputy assistant secretary of State for Asia from 2006 to 2008. “Alan helped us keep the peace in that volatile period in cross-Strait relations.”

His advice was not always heeded — most notably when tensions led to the firing of Chinese missiles at Taiwan and a show of force by a flotilla of U.S. warships under President Clinton.

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“Romberg was one of two or three officials who warned the secretary of state in 1995 that a visit to the U.S. by Taiwan president Lee Teng-hui was a bad idea and would trigger a crisis in U.S.-China relations,” Bader recalled. “Developments proved him right.”

Alan Demuth Romberg was born in White Plains, N.Y., on Dec. 1, 1938. He attributed his early interest in Asia to his father, a doctor who ran an Army field hospital in western China during World War II. He received a bachelor’s degree in 1960 from the Woodrow Wilson School of Public and International Affairs at Princeton University and a master’s degree in Soviet affairs from Harvard University in 1964.

After completing his undergraduate studies, he served two years in the Navy and was assigned to Taiwan.

His first marriage, to Elaine Ehrenfeld, ended in divorce. Survivors include his wife of 24 years, Nancy Henningsen of Bethesda; two children from his first marriage, Jon Romberg of Jersey City, and Laura Romberg of Cleveland; a stepson, Alex Southwell of Manhattan; a brother; and four grandchildren.

In addition to his Foreign Service career, from 1964 to 1985, Mr. Romberg served as director of the State Department’s Japan office and principal deputy director of the department’s policy planning office. He also was a State Department deputy spokesman, did stints on the National Security Council staff, was senior adviser to the U.S. Permanent Representative to the United Nations and was special assistant to the secretary of the Navy. He received Superior Honor and Distinguished Honor awards from the State Department.

Amid his government service, Mr. Romberg was a senior fellow at the Council on Foreign Relations from 1985 to 1994. In 2000, he joined the Stimson Center, a nonpartisan policy research center focused on national security where he was a distinguished fellow and co-directed the East Asia program.