Washington — Richard Spencer, the former secretary of the Navy, said he was fired before he could resign over the president's decision to intervene in an internal review of a Navy SEAL convicted of posing with the corpse, and downplayed a supposed backchannel offer to the White House that served as the justification for his ouster.

"I never threatened to resign. I do. I don't threaten," Spencer told CBS News correspondent David Martin after leaving the Pentagon on Monday. "I got fired."

Spencer stepped down at the request of Defense Secretary Mark Esper on Sunday amid an ongoing controversy over Navy SEAL Edward Gallagher, whose case attracted President Trump's attention.

Esper told reporters Monday that he fired Spencer after "losing trust and confidence in him regarding his lack of candor." He accused Spencer of secretly proposing a deal to the White House that would allow Gallagher to retire and retain his Trident pin, which denotes his status as a SEAL, a move Esper said was "completely contrary" to what the two had discussed.

In an interview Monday, Spencer told CBS News he spoke with White House counsel Pat Cipollone on November 15 and proposed an arrangement in which Gallagher would be allowed to retire as a SEAL if the president agreed not to intervene in the case and "let the Navy do its administrative work." Spencer said Cipollone called back the same day to decline the offer, saying the president would be involved.

"In order to preserve the resiliency of the naval institution, I had to step up and do something when it came to the Gallagher case," Spencer said.

Former Navy Secretary Richard Spencer in an interview outside the Pentagon on Monday, November 25, 2019. CBS News

Spencer acknowledged not telling Esper about the proposal.

"I will take the bad on me, for not letting him know I did that," Spencer said. "But as far as I was concerned, at that point, the president understood the deal. Arguably, he doesn't have to deal with anyone. He said, 'I'm going to be involved.' He sent a signed letter to me, an order with his signature on it, saying, 'Promote Edward Gallagher to E7,'" the rank of chief petty officer.

Esper acknowledged Monday that when confronted about his secret negotiations with the White House, Spencer "was completely forthright in admitting what had been going on."

Gallagher was court-martialed and faced nearly a dozen charges over allegations he opened fire on civilians during a deployment to Iraq, murdered a captured ISIS fighter and threatened fellow SEALs over reporting his actions. In July he was acquitted of the most serious charges, but convicted of posing for a photo with a corpse of the ISIS fighter. Following his conviction, the Navy decided to demote Gallagher, a move Mr. Trump ordered reversed.

Spencer said he promoted Gallagher after receiving the order and began developing the administrative peer review process, which could have led to Gallagher's Trident pin being revoked, expelling him from the Navy SEALs. Spencer said he explained the process to Esper's chief of staff and acting White House chief of staff Mick Mulvaney on November 19.

Spencer formally opened the Trident review board and notified relevant parties November 20, last Wednesday. The next day, the president tweeted, "The Navy will NOT be taking away Warfighter and Navy Seal Eddie Gallagher's Trident Pin," spurring reports that Spencer threatened to resign if the president issued a formal order preserving Gallagher's status, which he denied Monday.

He said General Mark Milley, the chairman of the joint chiefs of staff, urged him not to resign when the two spoke Friday. Spencer spoke to Esper on Saturday and briefed him on the events of the prior few days, and said the White House asked him to issue a statement denying he had threatened to resign, which he did publicly at an event that day.

Spencer said Monday that he doesn't think Mr. Trump "really understands the full definition of a warfighter."

"A warfighter is a profession of arms and a profession of arms has standards that they have to be held to, and they hold themselves to," he said.

In his resignation letter Sunday, Spencer said he opposed the president's insistence that Gallagher be allowed to remain a SEAL.

"I cannot in good conscience obey an order that I believe violates the sacred oath I took," he said. He wrote that the Constitution and the Uniform Code of Military Justice "are the shields that set us apart, and the beacons that protect us all." And Spencer said he had "strived to ensure our proceedings are fair, transparent and consistent."

Late Monday, the Navy officially announced the cancellation of Gallagher's Trident review board and that the former SEAL will be allowed to retire.