In a memoir of his time in the Trump Administration, Lt. Gen. H.R. McMaster recalls telling his wife he could not understand Russian President Vladimir Putin’s “hold” on President Trump.

The same book insists that during McMaster’s 13 months, the United States did much to revise its global strategies to face a changing world.

McMaster writes of struggling to help the president avoid mistakes, like responding to Putin’s flattery in embarrassing ways. Yet McMaster says he was not one of the officials around Trump who believed their job was to protect the country from his erratic or dangerous moves.

McMaster is both a scholar–author of Dereliction of Duty, an acclaimed history of U.S. military decision making in the Vietnam war–and a veteran of the wars in Iraq and Afghanistan. “I had been on the receiving end of policies and strategies developed in Washington that made no sense to me when I was in places like Baghdad or Kabul,” he said in an interview with NPR’s Steve Inskeep. So when offered the top NSC job, he accepted. “I saw it as an opportunity to help a disruptive president disrupt a lot of what needed to be disrupted in the area of foreign policy and in national security.”

That’s at least part of the story he’s telling in his new book – At War with Ourselves: My Tour of Duty in the Trump White House.

The other part recounts moments when McMaster had to navigate the fact that Trump himself was manipulated by aides at home and dictators abroad.

Speaking ahead of the release of his book August 27, he said he wouldn’t serve in a Trump administration again. “If President Trump was re-elected, of course I wish him [the] best and I want him to succeed. If our next president is Kamala Harris, I wish her the best, wish her to succeed,” he said on Morning Edition. “But I think my opportunity to serve in the Trump administration is used up.”

He does however urge others to serve and do the best they can.

On his working relationship with Trump, McMaster writes in an excerpt from his book: “I was the principal voice telling him that Putin was using him and other politicians in both parties in an effort to shake Americans’ confidence in our democratic principles, institutions and processes. Putin was not and would never be Trump’s friend. I felt it was my duty to point this out.”

But Trump made his own judgment calls, often taking a contrarian viewpoint.

“You know what President Trump was driven by is actually, I think, what President Obama was driven by and President George W. Bush was driven by when they were early in their administrations with Putin,” McMaster said. “Putin is a great liar. He’s a great deceiver.” He offers each new president flattery and the prospect of global cooperation. “So I would alert the president to this. He often didn’t want to hear it.”

McMaster talked of competing interests within Trump’s inner circle, from White House adviser Steve Bannon’s influence to Secretary of Defense Jim Mattis and Secretary of State Rex Tillerson often breaking protocol and working around McMaster’s National Security Council.

He characterized high level jobs in the White House in one of three ways.

“The first category are people who go into the administration to help the elected president determine his or her own agenda.” McMaster saw his role in this way.

“The second group of people come into any White House or any administration to advance their own agenda. The third group of people are people who are motivated mainly by the desire to protect the country and maybe the world from the president. And I think in the Trump administration, that second and third category of people were quite large.”

One of the dysfunctional moments McMaster describes in his book involves remarks Trump was giving in May 2017 at NATO headquarters in Belgium. Trump, like his predecessors, wanted to push NATO nations to spend more on their own defense. When McMaster learned that Trump had cut a line from his prepared speech affirming the U.S. commitment to defend its allies, he pressured a reluctant Tillerson and Mattis to join him in dissuading Trump from such a move. While they convinced him to modify the speech, Trump’s skepticism of the NATO alliance has never gone away.

In his current presidential campaign, Trump has again repeated that he might not support those NATO allies who aren’t meeting their commitment to spend 2% of their GDP on defense.

The radio version of this interview was produced by Lilly Quiroz, and the digital version was edited by Majd Al-Waheidi.