A Pentagon investigation into leaked classified information has widened to include two additional aides to U.S. Defense Secretary Pete Hegseth and his deputy, officials confirmed on Wednesday.

Dan Caldwell, a senior adviser to Hegseth, was escorted out of the building and placed on administrative leave after what one official described as an "unauthorized disclosure." Now, two more aides — Darin Selnick and Colin Carroll — are also on leave as the internal probe continues.

Selnick, recently appointed deputy chief of staff to Hegseth, and Carroll, who served as chief of staff to Deputy Defense Secretary Steve Feinberg, were both placed on leave this week. Officials said more names could be added as the investigation develops.

The probe stems from a March 21 memo by Hegseth’s chief of staff, Joe Kasper, which requested a review into "unauthorized disclosures of national security information involving sensitive communications." The memo also left open the possibility of polygraph testing.

The case has drawn attention given Caldwell’s role. He was previously identified in a leaked Signal message exchange as Hegseth’s key liaison with the National Security Council ahead of U.S. airstrikes against the Houthis in Yemen.

Caldwell has been a controversial figure in Washington. A veteran of the Iraq War, he had publicly questioned U.S. military commitments overseas. In a December 2024 interview with the Financial Times, Caldwell called the Iraq War "a monstrous crime" and argued the U.S. would have been better off avoiding prolonged deployments abroad.

He also voiced skepticism over U.S. military support for Ukraine and pushed for a leaner American footprint in Europe.

While the three aides were placed on leave due to the leak investigation, the move comes during a broader shake-up at the Pentagon since Hegseth assumed the role in January. High-profile firings have included the chairman of the Joint Chiefs of Staff, the Navy’s top admiral, the head of U.S. Cyber Command and several top military lawyers.

The White House and Pentagon have declined to comment on whether any criminal charges are expected as part of the investigation.

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