Wyoming Republican Liz Cheney is reported to have convinced the former staffers to write the January op-ed in an attempt to warn against potential use of the military to overturn the election.
The Washington Post op-ed, published just three days before the January 6th Capitol Riots, was penned by Ashton Carter, William Cohen, Mark Esper, Robert Gates, Chuck Hagel, James Mattis, Leon Panetta, William Perry, Donald Rumsfeld and Liz Cheney's own father, Dick. In it, they stated that Trump should accept that it was too late to question the results, and that utilizing the military to achieve Trump's political goals would be a dangerous step in the wrong direction.
Eric Edelman, a friend of Liz Cheney's who served as national security advisor for her father, said in an interview with The New Yorker that, "She was the one that generated it", adding that it was "because she was so worried about what Trump might do."
"It speaks to the degree that she was concerned about the threat to our democracy that Trump represented", he continued.
The same day that the op-ed came out, Liz Cheney and her husband Phil Perry distributed a 21-page memo that they had written to "combat Trump's post-election lies", reports the New Yorker. Cheney warned her Republican colleagues that voting to overturn the results of the election would "set an exceptionally dangerous precedent."
Cheney and Trump often butted heads; she was one of the few Republicans to vote in favour of his (second) impeachment.
The aforementioned events all represent a growing schism in the Republican party in which Cheney finds herself, and those who agree with her, to be the minority.