Navy SEAL Edward Gallagher had been accused of war crimes in a high-profile case but was found guilty of a lesser offense.

On November 15, Trump reversed the demotion handed down to him due to his conviction.

The defense department accused Navy Secretary Richard Spencer of privately proposing to the White House that if they did not interfere with misconduct proceedings against Gallagher, then Gallagher would retire without being expelled from the elite SEAL force.

Spencer allegedly did not share his proposal with Defense Secretary Mark Esper.

Esper asked for Spencer's resignation "after losing trust and confidence in him regarding his lack of candor over conversations with the White House," the Department of Defense said in a statement.

Esper said he was "deeply troubled by this conduct."

The US Navy has launched a procedure under which a peer review board could strip Gallagher and three other members of his unit of their Trident pins -- effectively booting them from the SEALS.

But the intervention of Trump -- commander-in-chief of the US military -- has thrown that process into doubt.

Trump declared on Twitter on Thursday that "The Navy will NOT be taking away Warfighter and Navy Seal Eddie Gallagher's Trident Pin."