James Mann is author-in-residence at the Johns Hopkins School of Advanced International Studies. His most recent book is “The Obamians: The Struggle Inside the White House to Redefine American Power.”

Standing alongside President Obama in the White House Rose Garden on Wednesday, Samantha Power thanked him for nominating her as ambassador to the United Nations — and then quickly referred to her 2002 book, “A Problem From Hell: America and the Age of Genocide.”

“From the day I met you and you told me that you had spent a chunk of your vacation reading a long, dark book on genocide,” Power said to the president, “I knew you were a different kind of leader, and I knew I wanted to work for you.”

In a sense, Power was bowing to the inevitable. That book, which won a Pulitzer Prize and a National Book Critics Circle Award, is what first brought her to national attention, and it remains the single piece of work for which she is best known. “A Problem From Hell” argued for military intervention to prevent genocide in the Balkans and Rwanda, and it left Power caricatured as a modern-day Joan of Arc. A couple of years ago, the National Interest placed Power on its cover with a headline that screamed, in blood-red type: “Interventionista!”

Her nomination has raised speculation about whether she will push for a more interventionist U.S. foreign policy, particularly in places such as Syria. No doubt, journalists and diplomats will be reading or re-reading “A Problem From Hell” and other Power writings looking for clues, as will members and staff of the Senate Foreign Relations Committee, preparingto grill her at her confirmation hearing over footnotes or obscure sentences in long-forgotten articles. (I imagine that the administration officials getting ready for the Senate ritual have already done searches of her prose to track down every mention of the words “Israel” and “Palestinians.”)

Yet, for those seeking to move beyond the interventionist stereotype and gain a more genuine understanding of Power, “A Problem From Hell” is the wrong book to read. More revealing is her second book, “Chasing the Flame.” It is a lesser-known work but no less ambitious, and it is more relevant to what Power will try to achieve at the United Nations over the next three years, as well as more indicative of the intellectual evolution she has made from journalist and advocate to public official.

“Chasing the Flame” is an account of the life of a Brazilian-born U.N. officialnamed Sergio Vieira de Mello. He was not well known in the United States, but he was the United Nations’ main troubleshooter, serving for decades in hot spots such as Bosnia (where Power met him), Lebanon, Cambodia, Rwanda, Sudan, Afghanistan and finally, Iraq, where he was in charge of U.N. operations after the fall of Saddam Hussein. He died in Baghdad in a bombing in the summer of 2003.

The book is not a hagiography. It describes at length Vieira de Mello’s foibles. But Power writes admiringly of her subject, particularly the way he gravitated from his early idealism to the complexities of problem-solving. He brought the unique perspective of someone who spent his time not in New York or Washington, but on the ground amid crisis after crisis.

“He started out as a humanitarian, but by 2003 he had become a diplomat and politician, comfortable weighing lesser evils,” Power observed.

“His professional journey led him to believe the world’s leaders needed to do three big things. First, they had to invest far greater resources in trying to ensure that people enjoyed law and order. Second, they had to engage even the most unsavory militants. Even if they did not find common ground with rogue states or rebels, at least they might acquire a better sense of how to outmaneuver them. And third, they would be wise to orient their activities less around democracy than around individual dignity.”

Power dedicated “Chasing the Flame” to her first mentor, Morton Abramowitz, a former Foreign Service officer, ambassador and intellectual. Like Power, he was a leading proponent of military intervention in the Balkans. Like Vieira de Mello, he has sometimes sounded the theme that in pursuing humanitarian goals, it is important to talk even to unsavory regimes.

In “Chasing the Flame,” Power seems to be wrestling with how to transcend simple moralism and move beyond a preoccupation with American military intervention in dealing with humanitarian challenges. In the process of writing, she seems to be charting her own evolution as well.

In an interview I had with her two years ago, she argued that “A Problem From Hell” had been widely misinterpreted. It had not been merely a treatise on behalf of military intervention, she said, but a plea to give American presidents and other world leaders a “toolbox” with a wide range of options to prevent mass killing. She emphasized the importance of other approaches — economic sanctions, freezes on assets, bans on travel, denunciations of human rights abusers and referrals to the International Criminal Court.

These tools of foreign policy hardly originated with Power — and she never claimed they did — but it’s worth noting that over the past four years, they have formed the thrust of the Obama administration’s efforts in dealing with an array of countries, among them Iran, Syria, Libya and North Korea.

For the past 40 years, a series of prominent Americans have often used the post of U.S. ambassador to the United Nations as a bully pulpit, delivering fiery speeches that attract attention at home and abroad. The practice started with Daniel Patrick Moynihan and was continued in various ways by Andrew Young, Jeanne Kirkpatrick, Madeleine Albright and John Bolton. Their speeches set forth their views of America’s role in the world.

It seems doubtful that Power will try to fit herself into this tradition. Based on “Chasing the Flame,” I suspect that she will be drawn less to grand pronouncements than to the problem of making the United Nations more effective around the world, even in grubby, obscure places that may be experiencing political or humanitarian crises but where there is not much of an American role. These are places like East Timor, where Vieira de Mello worked, or sub-Saharan Africa.

The United Nations is not merely the Security Council and the General Assembly, but a huge international bureaucracy dealing with crises and chronic problems the United States can’t address on its own. While it’s easy to ridicule it or write it off, in “Chasing the Flame,” Power grasped the importance of making it work better.

Strengthening U.N. operations may seem marginal to the Obama administration’s overall foreign policy, but in fact it is linked to the president’s broader vision.

Certainly, over the next three years Obama will be preoccupied with a handful of big and problematic countries, such as Syria, Iran and North Korea. And he’ll have to deal with the major powers, including China and Russia, Britain and France. (Power herself, if confirmed, will be spending a lot of time dealing with representatives of these countries at the Security Council.)

Yet beyond these immediate crises, Obama has seemed eager to limit America’s military footprint around the globe, to shift gradually to a more modest U.S. role in the world and to give greater scope and power to the operations of the United Nations. In his Nobel Peace Prize speech, Obama declared that “America’s commitment to global security will never waver. But in a world in which threats are more diffuse, and missions more complex, America cannot act alone.” He added, “That’s why we must strengthen U.N. and regional peacekeeping.”

Power served as Obama’s closest aide in drafting that speech. And she wrote, in “Chasing the Flame,” that Vieira de Mello had “wondered, with all the ingenuity that fueled progress in the developed world, why so little of it was ever made available to assist what he called ‘convalescing states.’ ”

Power is likely to get the opportunity to put these ideas into effect at the United Nations. In her daily work, proposals for U.S. military intervention will seem remote, if not entirely irrelevant.

Read more from Outlook:

Five myths about Obama’s foreign policy

How, when and whether to end the war in Syria

In Syria’s war, the lines that matter aren’t red

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