Shortly before Donald Trump detonated a NATO summit, shanked the beleaguered British prime minister and prepped for a face-to-face love session with Vladimir Putin, his White House quietly divested itself of a senior official hawkish on Russia and bullish on the transatlantic military alliance.

The circumstances of retired Army Colonel Richard Hooker’s departure from the National Security Council on June 29 are in dispute. It’s not clear whether Hooker was forced out or if his detail on the NSC came to its natural end. But what’s not in doubt is that for the past 15 months, Hooker was senior director for Russia, Europe and NATO.

And just as his new boss, National Security Adviser John Bolton, was preparing to travel to Moscow to meet with Putin on June 27 to lay the groundwork for Trump’s visit, Hooker was packing up his desk. Now, he’s headed back to the National Defense University, the crown jewel of the Pentagon’s cross-service military-education system, which had loaned him to the NSC. Hooker is the latest NSC staffer to leave as Bolton reconfigures the influential policymaking body in his image. Like Hooker, Bolton has long viewed Russia a strategic threat to the United States, and accused Putin of lying to Trump about interfering in the 2016 election.

Hooker, who is highly respected in military circles, would not comment for this story, and an NSC spokesperson declined to comment on the record as well. But many sources familiar with him portrayed him as the sort of consensus defense official common in both Republican and Democratic administrations in the pre-Trump era.

Hooker, who has deployed to Somalia, Bosnia, Kosovo, Iraq and Afghanistan, is a strong advocate of a U.S. military presence in Europe and the NATO alliance, and skeptical of Russian intentions on the continent. His knowledge of NATO is intimate, having previously served as dean of the NATO Defense College in Rome. At the Trump NSC, Hooker was deputy to Fiona Hill, who has the Europe and Russia portfolios and whose pre-administration criticism of Russia has garnered her a reputation as a White House bulwark against Trump’s coziness with Putin. Bolton brought Hill with him to Moscow when he met with Putin at then end of June.

“ Two government officials said it wasn’t Hooker’s policy views that got him into trouble. Hooker ended his tour on the National Security Council early after he discussed information pertinent to Russia with foreign officials. ”

“[Hooker] is committed to a strong U.S. presence in Europe and has the highest respect for allies and the NATO alliance. He was and is concerned about NATO's conventional deterrent in the Baltics and East Europe,” said Joseph Collins, a retired Army colonel who directs the Center on Complex Operations at the National Defense University. “He is a strong supporter of better NATO burden-sharing and improving the economic contribution of our NATO allies.”

But two government officials said it wasn’t Hooker’s policy views that got him into trouble. Hooker ended his tour on the National Security Council early after he discussed information pertinent to Russia with foreign officials without proper authorization, according to two government officials.

The United States routinely shares intelligence with its allies, but the information Hooker allegedly shared was information that had “not been approved to be shared with allies,” according to one government official with knowledge of the incident. It’s not clear if these concerns about improper information sharing were communicated to Hooker as part of the discussion around his departure from NSC.

A former NSC official strongly denied the two government officials’ account. From this official’s perspective, Hooker did not discuss Russia with any foreign government outside official sanction. According to this official, the retired colonel was not fired, for that or for any other reason. Instead, Hooker’s secondment from NDU had already expired, and he was overdue for return.

Several colleagues expressed astonishment and disbelief that Hooker would have been accused of compromising information and doubted he would have done so. Two of them believed Hooker was always supposed to return to NDU when his NSC detail expired and said that remains the plan. NDU representatives did not return messages seeking comment.

“As a consummate professional, Hooker is apolitical and close-mouthed about his duties. He is the last person to tell tales outside of work,” said NDU’s Collins, who has worked for Hooker and for whom Hooker has worked; the two retired officers have known each other for decades.

“ As a consummate professional, Hooker is apolitical and close-mouthed about his duties. He is the last person to tell tales outside of work. ” — Joseph Collins

Like Hill, Hooker was hired by his fellow Army officer, H.R. McMaster. Trump fired McMaster in March, but NSC officials asked Hooker to stay on awhile to ease the transition to McMaster’s replacement, John Bolton. Since Bolton’s arrival in April, several NSC officials his predecessors had hired, including Mideast NSC officials Joel Rayburn, James Sindle, and Mike Bell, have left, as the National reported last week. Politico reported on Friday that Bolton has removed another NSC staffer, Jennifer Arangio of the international-operations office.

Former and current NSC officials agree it’s Bolton’s prerogative to reshape the NSC staff as he sees fit.

“When a new NSC adviser was brought on board, [Hooker’s] return to NDU or another assignment was a given,” said Collins, who praised Hooker’s intellect and dedication: “He has a work ethic that would kill a mule. Always first one in and last one out.”

Bolton has brought on Mira Ricardel, who clashed with Defense Secretary Jim Mattis during the early days of the administration, as his deputy, and Fred Fleitz as his deputy chief of staff.

As The Daily Beast has previously reported, Fleitz said it was “impossible” to know if the Kremlin was responsible for the hacking of the Democratic National Committee in 2016—the Justice Department just indicted 12 Russians for the attack—and argued that sanctioning Moscow for election interference was merely “an attempt to sabotage the Trump administration’s Russia policy.”

Published in conjunction with Just Security.