Henry Rowen in 1984. (Ed Souza/Stanford University )

Henry S. Rowen, a leading economist and public policy intellectual who headed the Rand Corp. when his close friend Daniel Ellsberg set off a national furor by leaking the research institute’s copy of the Pentagon Papers on the Vietnam War, died Nov. 12 in Menlo Park, Calif. He was 90.

His death was announced by the Santa Monica, Calif.-based Rand Corp. and Stanford University, where he had taught for many years after leaving Rand in 1972. The cause was an apparent heart attack, said his son Christopher Rowen.

Mr. Rowen made his reputation in the 1950s and 1960s, exemplifying the class of public policy thinkers who moved among universities, high-ranking government positions and prominent think tanks.

He helped shape the federal government’s approaches to defense and domestic issues for decades, and the competition for Mr. Rowen’s abilities led him at one point to buy and sell five houses in about six months, a seemingly nonstop exposure to the bicoastal real estate market that he recalled as “painful.”

As a young, Oxford-trained Rand economist in the 1950s, he developed an expertise in long-term planning studies that influenced military spending and cutbacks as well as budgetary planning by federal agencies.

Three Rand presidents in 1973, from left: Donald Rice, third president; Franklin Collbohm, first president; and Henry S. “Harry” Rowen, second president. (Rand Corp. )

In 1961, he was among the analytical, reformist thinkers brought to the Pentagon by then-Defense Secretary Robert S. McNamara at the start of the Kennedy administration. As deputy assistant secretary of defense for international security affairs, he focused on long-range NATO planning amid Cold War threats in Europe.

After a brief stint as assistant director of the U.S. Bureau of the Budget, he returned to Rand in 1967 to take over from its founding president, Franklin Coll­bohm, who had been in the post for 20 years.

Rand, formed initially to serve the Air Force, had taken its name from the acronym for research and development — “R and D.” By the time Mr. Rowen took the reins, the independent, nonprofit organization had expanded beyond its original mandate to conduct wide-ranging national security studies.

Mr. Rowen further broadened Rand’s work into domestic policy studies, including a large-scale project examining New York’s endemic municipal problems for then-Mayor John V. Lindsay. Many within Rand saw the undertaking as a distraction from the organization’s core mission, it was reported at the time, and the institution became immersed in deeply politicized arguments over the city’s housing, police and fire departments.

Rand continued diversifying its portfolio over the decades and today divides its time roughly evenly between defense and domestic studies, including work on education and health-care policy, Rand spokesman Warren Robak said.

The incident that most roiled Mr. Rowen’s tenure at the helm of his organization centered around a Rand copy of the Pentagon Papers, a 47-volume top-secret history of the Vietnam War that McNamara had commissioned in 1967. The analysis showed a gap between stark internal assessments of the war’s progress and optimistic public statements by military leaders and elected officials overseeing the war.

As a newly elected president in 1969, Richard M. Nixon tasked his national security adviser, Henry A. Kissinger, with preparing policy options on the war. Kissinger called Mr. Rowen, who in turn tapped Ellsberg, who had grown close to Mr. Rowen while working as an analyst at the Pentagon and at Rand.

Ellsberg, a former Marine Corps officer who had once been hawkish on Vietnam, increasingly saw dismal prospects for an American victory there. Those feelings only intensified when Ellsberg, who had a high-security clearance, obtained access to Rand’s copy of the Pentagon Papers in order to aid his study for Kissinger. Mr. Rowen had pushed for Ellsberg’s access, reputedly against the advice of others wary of the analyst.

Ellsberg tried unsuccessfully to get antiwar politicians to make the papers public before he persuaded the New York Times to print them in 1971.

The Nixon White House tried to use the courts to enjoin the Times and later The Washington Post from running excerpts of the Pentagon Papers. But the U.S. Supreme Court ruled 6 to 3 in favor of their continued publication, saying the government had not met its burden of proving national security concerns that trumped the newspapers’ First Amendment rights.

The incident had an enduring effect on relations between the government and the public, and between the government and the media. It also ended Mr. Rowen’s career at Rand, leading to his resignation in 1972.

“The Navy has a rule that if a ship runs aground, there’s never any excuse,” Mr. Rowen later said. “And I did actually have some responsibility for it. . . . And trusting Dan was a bad mistake.” (His family said Mr. Rowen and Ellsberg did not resume their former cordial relationship.)

Ellsberg told National Public Radio in 2010 that copying and releasing the papers was difficult but necessary. He said he recognized “that I was going to harm the career of my closest friend, Harry Rowen. And that was very anguishing.”

However, he added, “I couldn’t see any way to avoid that.”

Henry Stanislaus Rowen, known to friends as Harry, was born in Boston on Oct. 11, 1925. After Navy service as a radar repairman in World War II, he received a bachelor’s degree in chemical engineering from the Massachusetts Institute of Technology in 1949. Six years later, he obtained a master’s degree in economics from the University of Oxford in England.

Mr. Rowen was a resident of Palo Alto, Calif. Survivors include his wife of 64 years, Beverly Griffiths Rowen of Palo Alto; six children, Hilary Rowen of Menlo Park, Michael Rowen of Portola Valley, Calif., Christopher Rowen of Santa Cruz, Calif., Sheila Rowen of San Jose, Calif., Diana Rowen of Bethesda, Md., and Nicholas Rowen of Fort Collins, Colo.; and nine grandchildren.

Mr. Rowen’s departure from Rand did not halt what had been a long and productive career. In addition to writing and editing books and studies, he joined the Stanford faculty in 1972 and became a professor of public policy and management and a senior fellow of the Stanford Institute for International Studies and the Hoover Institution.

After his formal retirement in 1995, he was associated with the Stanford Program on Regions of Innovation and Entrepreneurship, which analyzes Asia’s high-tech industry.

Under President Ronald Reagan, he chaired the National Intelligence Council in the early 1980s. He took an academic leave, from 1989 to 1991, to serve in President George H.W. Bush’s administration as assistant secretary of defense for international security affairs.

In 2004 and 2005, he was a member of the presidentially appointed Commission on the Intelligence Capabilities of the United States Regarding Weapons of Mass Destruction, which issued a blistering report on the credibility of U.S. intelligence agencies leading up to the U.S.-led invasion of Iraq in 2003.

The assessment said that the government “knows disturbingly little about the nuclear programs of many of the world’s most dangerous actors,” and that the intelligence estimates relied on to justify the Iraq invasion were greatly exaggerated.