A Pentagon investigation into leaks of classified and sensitive information has expanded to include two more aides to Defense Secretary Pete Hegseth and his deputy, officials said on Wednesday.
Reuters was first to report on Tuesday that Dan Caldwell, a senior adviser to Hegseth, was escorted out of the Pentagon and put on administrative leave after what one U.S. official described as an “unauthorized disclosure.”
Following Caldwell’s departure, less senior officials Darin Selnick, who recently became Hegseth’s deputy chief of staff, and Colin Carroll, who was chief of staff to Deputy Defense Secretary Steve Feinberg, were put on administrative leave, officials said.
More Pentagon officials could also be named as the investigation continues, officials say.
President Donald Trump’s administration has aggressively pursued leaks, an effort that has been enthusiastically embraced by Hegseth at the Pentagon.
A March 21 memo signed by Hegseth’s chief of staff, Joe Kasper, requested an investigation into “recent unauthorized disclosures of national security information involving sensitive communications.”
Kasper’s memo left open the possibility of a polygraph test, although it was unclear if Caldwell, Selnick and Carroll were subjected to one.
Selnick is a retired Air Force officer who, prior to becoming deputy chief of staff, had been acting as lead adviser on personnel and readiness policies. Carroll, a Marine Corps veteran, had previously worked for AI-powered defense startup Anduril Industries. Politico previously reported that Selnick and Carroll were put on leave.
Caldwell, in particular, played a critical role as an adviser to Hegseth.
His importance was underscored in a leaked text chain on Signal disclosed by the Atlantic 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 had drawn attention in Washington for past views that critics have called isolationist, but which advocates said sought to right-size America’s defense priorities.
Caldwell, who had deployed to Iraq, was quoted as saying before going to the Pentagon that the U.S. would have been better off if U.S. troops had stayed home.
“I think the Iraq War was a monstrous crime,” Caldwell told the Financial Times in December 2024.
He was also a skeptic of U.S. military assistance to Ukraine and advocated for U.S. retrenchment from Europe.
The decision to put Caldwell, Selnick and Carroll on administrative leave is separate from a wave of firings since Hegseth, a former Fox News host and combat veteran, took over the Pentagon in January.
Those firings of top brass have included the chairman of the Joint Chiefs of Staff, the top admiral in the Navy, the head of U.S. Cyber Command and the top U.S. military lawyers. Reuters was first to report last week the firing of the U.S. military representative to the NATO Military Committee.
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