WASHINGTON, United States (AFP) — President Donald Trump named US Army Lieutenant General HR McMaster as his new national security advisor on Monday, taking over the post left vacant after Michael Flynn’s resignation.

Trump called McMaster, a career Army officer and prominent expert on counterinsurgency warfare, a “man of tremendous talent and tremendous experience.”

“He is highly respected by everyone in the military and we’re very honored to have him,” Trump told reporters at his Mar-a-Lago residence in Palm Beach, Florida.

He spoke sitting alongside McMaster, who was dressed in uniform. Trump said McMaster would work alongside acting national security advisor Keith Kellogg, a retired three-star general, in a “very, very special” collaboration.

McMaster, who heads the Army Capabilities and Integration Center and is deputy commanding general of the Futures Center at US Army Training and Doctrine Command at Fort Eustis, previously directed a transparency task force in Afghanistan.

He also held key roles in the Iraq War and Gulf War, and is known for his criticism of the US military’s involvement in the Vietnam War.

One of the books he authored is pointedly titled “Dereliction of Duty: Lyndon Johnson, Robert McNamara, the Joint Chiefs of Staff and the Lies That Led to Vietnam” (1997).

Trump, McMaster and Kellogg ignored questions from reporters after the announcement, including over whether the new national security advisor would be allowed to hire his own staff.

Robert Harward, a retired vice admiral and former Navy SEAL, reportedly turned down Trump’s offer of the job last week over concerns he would not be able to bring in his own team to staff the National Security Council. Other reports said he was put off by apparent chaos in the White House.

Trump had interviewed a handful of candidates for the post in recent days, including John Bolton, who served as Washington’s United Nations ambassador under Republican president George W. Bush.

The president hinted at a future role in his administration for Bolton. “We’ll be asking him to work with us in a somewhat different capacity,” Trump said, without any further details.

Flynn was forced to resign last week after misleading Vice President Mike Pence about discussions he had held with the Russian ambassador to the United States concerning US sanctions on Moscow.