A top adviser to Defense Secretary Pete Hegseth was escorted out of the Pentagon on Tuesday after allegedly being identified during an investigation into leaks at the department.

Dan Caldwell was placed on administrative leave for ‘an unauthorized disclosure,’ an official told Reuters.

‘The investigation remains ongoing,’ the official said without providing details about the nature of the alleged disclosure, including whether it was made to a journalist or to someone else. 

The move comes after a March 21 memo ordering a Pentagon investigation into leaks ordered by Hegseth’s chief of staff Joe Kasper.

Kasper requested an investigation into ‘recent unauthorized disclosures of national security information involving sensitive communications.’

His memo left open the possibility of a polygraph, although it was unclear if Caldwell was subject to one.

Top Pentagon adviser Dan Caldwell was escorted from the building for leaks

Although Caldwell is not as well known as other senior Pentagon officials, he has played a critical role as an adviser to Hegseth.

His importance was underscored in a leaked text chain on Signal disclosed by The Atlantic magazine last month.

In it, Hegseth named Caldwell as the best staff point of contact for the National Security Council as it prepared for the launch of strikes against the Houthis in Yemen.

Caldwell, a Marine Corps veteran, was head of the transition team at the Pentagon and took the lead on hiring staff at the Defense Department.

He and Hegseth have a longtime friendship. Caldwell was by Hegseth’s side on Capitol Hill as the former Fox News host fought to keep his nomination alive during questions about his treatment of women.  

Before joining Hegseth’s team, Caldwell worked for Defense Priorities and Concerned Veterans for America.

Defense Priorities, a conservative think tank funded by the Koch brothers, advocates for more restrained US foreign policy.

Concerned Veterans for America has strong ties to Republican lawmakers on the veterans and armed services committees – and it has enjoyed a friendly relationship with President Donald Trump in the past. 

It’s also funded by the Koch brothers and is where Hegseth and Caldwell met. 

Caldwell and Hegseth, like Vice President J.D. Vance, all share the same isolationist view of foreign policy. Similar in age, they are all veterans of either Iraq or Afghanistan.

Don Trump Jr., the president’s oldest son, is said to share that isolationist view point.

Caldwell, in an interview with Politico last year when he worked Defense Priorities, said of his time in Iraq: ‘We didn’t go in with this attitude of doing harm. We wanted to fight. We didn’t want to unnecessarily hurt anybody. Yet our presence did unintentionally hurt people. A lot of people.’ 

And he told the Financial Times in December: ‘A lot of times when President Trump is railing against American foreign policy failures, he is his most focused and righteously angry. And that really appealed to me in 2016.’

Caldwell, while at the Pentagon, pushed for the U.S. to dramatically reduce its military footprint abroad.

He also downplayed the significance of the American-Israeli alliance.

But there are reports that Caldwell clashed with Hegseth and Trump on Iran. Caldwell had an more open-mind when it came to the Middle East nation instead of Trump’s tough-on-Iran rhetoric.

In an essay for Foreign Affairs, Caldwell argued the U.S. should ‘significantly’ pull back from the Middle East, where he believed that ‘American interests are less pronounced.’

Defense Secretary Pete Hegseth (above) worked with Caldwell at Concerned Veterans for America before they both joined the Trump administration

President Donald Trump in the Oval office

Caldwell, during his military service, worked in the Marine Corps Presidential Support Program, where he served as a member of the security force at the presidential retreat at Camp David. 

He later deployed to Iraq in support of Operation Iraqi Freedom and conducted operations in Al Anbar and Ninawa provinces. 

After he left the service he worked worked for Rep. David Schweikert, a Republican congressman from Arizona, from 2011 to 2013, focusing on veterans and defense issues.