Bill Keller, who led The New York Times through its rocky dealings with WikiLeaks, came to regard founder Julian Assange as undeniably smart “but arrogant, thin-skinned, conspiratorial and oddly credulous.”

That was the staff’s conclusion, the executive editor writes in the introduction to a forthcoming e-book about WikiLeaks—the first ever published by the newspaper.

The book— Open Secrets: WikiLeaks, War and American Diplomacy—will go on sale Monday through such websites as Barnes & Noble and Amazon, at a cost of $5.99. It includes many of the leaked documents as well as expanded stories and essays about the issues swirling around the shadowy group.

Keller (who as a Pulitzer Prize-winning foreign correspondent knows how to write) describes Assange as “a source who was elusive, manipulative and volatile.” And he indulges his inner John LeCarre: “An air of intrigue verging on paranoia permeated the project, perhaps understandably, given that we were dealing with a mass of classified material and a source who acted like a fugitive—changing crash pads, e-mail addresses and cell phones frequently.”

The book’s introduction also serves as a defense of the Times’ role in examining and distributing some of the hundreds of thousands of pages of secret documents that critics say gave Assange a mainstream media stamp of approval.

“I hope it doesn’t come across as defensive,” Keller said in an interview. “I’m fully aware there are honorable people who are skeptical about the whole thing. There are people who think what WikiLeaks did was horrible. There are people who think we should have had nothing to do with this…

“Julian Assange was a source. Sources are often complicated. Sources often come with their own agenda. He had no input into our journalistic decision-making.”

In the article, Keller describes how his relationship with Assange deteriorated last July when the Times—along with The Guardian and Der Spiegel—published some of the Afghanistan war logs provided by WikiLeaks. When the Times declined to link to the WikiLeaks site, out of concern the raw documents would include identifying information that could make people targets of the Taliban, Assange expressed his unhappiness in one of several phone calls.

“Where’s the respect?” he asked Keller.

Assange was further infuriated by a sharply negative front-page Times profile that he denounced as a smear. By the time WikiLeaks was ready to release 250,000 State Department cables in October, Assange attempted to impose one condition on The Guardian: that the material could not be shared with the Times. After becoming suspicious on that count, Keller writes, Assange burst into the London office of Guardian Editor Alan Rusbridger, and during an eight-hour meeting “raged intermittently against the Times… while The Guardian journalists tried to calm him.”

Rusbridger called Keller to relay Assange’s demand for a front-page Times apology, “buying time for the tantrum to subside.”

(Asked for comment, Rusbridger says he “enjoyed Bill's reflections” but would hold off on his own. Why? “The Guardian has, by coincidence, its own book out next week, with my own Keller-style reflections.”)

“Julian Assange was a source. Sources are often complicated. Sources often come with their own agenda. He had no input into our journalistic decision-making.”

In November, Washington Bureau Chief Dean Baquet held a tense meeting at the State Department with officials from State, the White House, CIA, FBI, and Pentagon to vet the cables to protect confidential sources and informants. Keller described the Obama administration’s efforts as “sober and professional,” contrasting it with George W. Bush warning him in the Oval Office several years ago that “we should share blame for the next terrorist attack” if the paper published information on domestic surveillance and anti-terror efforts.

Keller argues that classified leaks “are part of the way business is conducted in Washington.” He amplifies the point with a mild swipe at a competitor, writing, “Look no further than Bob Woodward’s all-but-authorized accounts of the innermost deliberations of our government.”

Reflecting on his dealings with Assange, who is now out on bail while Swedish prosecutors pursue sexual assault charges against him, Keller told me: “I don’t think he really gets in his gut how journalistic organizations work, particularly American journalistic organizations. Julian tended to see American news organizations as not observers but as actors and advocates. When things happened that he didn’t like, he tended to see a conspiracy behind it.”

In the interview, Keller marveled at both the speed and modest cost of publishing the e-book—which includes material on the recent street protests that toppled the president of Tunisia.

“I hope it gets some traction, and if it does we’ll do it again,” he said. “It’s not a huge gamble in terms of money.” Keller described e-books as the industry’s fastest-growing sector and said the Times will soon begin publishing a separate bestseller list for digital books. He sees Open Secrets as particularly appealing to teachers, students, and foreign-policy scholars.

Asked about a recent report that the Times will mirror WikiLeaks by setting up a site where leakers can send material anonymously, Keller said it is in the early planning stages and that there are technical, legal, and ethical issues to be resolved. But he likes the idea “that we could set up something for people who are nervous about their whistle-blowing.”

As for his future sideline as a columnist, Keller regards it as “kind of rejuvenating.” But he recalls his last attempt during “my years in exile—the Howell years,” when Howell Raines had beaten him out for the executive editor’s job and he sought refuge in the opinion pages.

“I spent weeks on what must have been the most overreported and over-thought column in the history of columns,” he recalled. Then 9/11 happened, and his piece on western water rights never ran.

Howard Kurtz is The Daily Beast's Washington bureau chief. He also hosts CNN's weekly media program Reliable Sources on Sundays at 11 a.m. ET. The longtime media reporter and columnist for The Washington Post, Kurtz is the author of five books.