Trump Chooses H.R. McMaster as National Security Adviser

The choice continued Mr. Trump’s reliance on high-ranking military officers to advise him on national security. Mr. Flynn is a retired three-star general and Mr. Mattis a retired four-star general. John F. Kelly, the homeland security secretary, is a retired Marine general. Mr. Trump’s first choice to replace Mr. Flynn, Robert S. Harward, who turned down the job, and two other finalists were current or former senior officers as well. General McMaster will remain on active duty.

General McMaster had the aura of disruption that Mr. Trump has valued in several cabinet secretaries, said a senior administration official who insisted on anonymity to describe internal deliberations. Another candidate, Lt. Gen. Robert L. Caslen, the superintendent of West Point, impressed Mr. Trump as being “from central casting,” the official said. But the president wanted him to stay at West Point, which he reveres.

General McMaster, 54, made a name for himself as a young officer with a searing critique of the Joint Chiefs of Staff for their performance during the Vietnam War and later criticized the way President George W. Bush’s administration went to war in Iraq.

As a commander, he was credited with demonstrating how a counterinsurgency strategy could defeat militants in Iraq, demonstrating the promise of an approach that Gen. David H. Petraeus adopted to shift momentum in a war the United States was on the verge of losing.

Stocky, smart and soft-spoken with a sense of humor, General McMaster, for all his war-making experience, has little background in navigating Washington politics, which could be a challenge for him in his new role with a fractious national security team to corral.

His task now will be to take over a rattled and demoralized National Security Council apparatus that bristled at Mr. Flynn’s leadership and remains uncertain about its place in the White House given the foreign policy interests of Stephen K. Bannon, the former Breitbart News chairman who is the president’s chief strategist.

Meeting with Generals at Mar-a-Lago in Florida. Very interesting!

— Donald J. Trump (@realDonaldTrump) Feb. 20, 2017

Most of the National Security Council staff is composed of career professionals, often on loan from military or civilian agencies, and they have complained privately about being shut out of their areas of expertise and kept in the dark about important decisions. Mr. Trump’s aides look on many of those holdovers from the last administration with suspicion, blaming them for leaks. The atmosphere has grown so toxic that some council staff members have said they feared they were being surveilled.

Several security council aides said Monday that they learned about General McMaster’s selection the same way the public did and expressed concern that Mr. Flynn’s associates, derisively called the Flynnstones, would stick around. But General McMaster has the advantage of having served in Iraq with some officials currently on the staff, including aides like Derek Harvey and Joel Rayburn.

Mr. Trump said Keith Kellogg, another retired lieutenant general, would remain as the council’s chief of staff. Mr. Kellogg has been acting national security adviser since Mr. Flynn’s resignation a week ago and was one of the four candidates interviewed by Mr. Trump on Sunday for the permanent job. Mr. Trump made no mention of K. T. McFarland, the top deputy national security adviser, and whether she would stay.

General McMaster thanked Mr. Trump but gave no insight into his plans. “I’m grateful to you for that opportunity,” he told the president, “and I look forward to joining the national security team and doing everything that I can to advance and protect the interests of the American people.”

The other finalist was John R. Bolton, a former ambassador to the United Nations under Mr. Bush. This was the second time Mr. Bolton, an outspoken conservative, had been considered for a high-level post in Mr. Trump’s administration. Mr. Trump praised Mr. Bolton on Monday and said he would find a position for him.

“We had some really good meetings with him. Knows a lot,” the president said. “He had a good number of ideas that I must tell you I agree very much with. So we’ll be talking with John Bolton in a different capacity.”

General McMaster has served as director of the Army Capabilities Integration Center at Fort Eustis in Virginia since 2014. A West Point graduate with a doctorate in military history from the University of North Carolina at Chapel Hill, he commanded a unit that clashed with Iraq’s Republican Guard in one of the biggest tank battles of the Persian Gulf war in 1991, earning him the Silver Star.

But he came to prominence with his 1997 book, “Dereliction of Duty,” which critiqued the Joint Chiefs for not standing up to President Lyndon B. Johnson during the Vietnam War. He cemented his reputation in 2005 during the second Iraq war when he led the Third Armored Cavalry Regiment in regaining control of Tal Afar.

The operation was cited as a textbook example in a manual on counterinsurgency doctrine prepared by General Petraeus. Another commander who had a role in drafting that manual was Mr. Mattis, then a Marine general. General Petraeus took a similar approach when he assumed command in Iraq in 2007 with a surge of troops authorized by Mr. Bush.

Yet General McMaster was passed over for the rank of general until General Petraeus and Robert M. Gates, then the defense secretary, rallied support for him.

One protégé from that time was Mr. Cotton, who nearly resigned from the Army in 2007 when it looked as though General McMaster might be forced out.

After Mr. Flynn’s resignation, Mr. Cotton reached out to Mr. Pence, Mr. Bannon and Reince Priebus, the White House chief of staff, about General McMaster and forwarded his résumé and personal phone number, according to several officials involved in the process. Another advocate for the general was Chris Brose, the staff director of the Senate Armed Services Committee, whose chairman is Mr. McCain.

Mr. McCain, who has been sharply critical of Mr. Trump in recent days, praised the appointment and said, “I could not imagine a better, more capable national security team than the one we have right now.”