Two top officials of former president George W. Bush were responsible for the stinging letter signed by 10 former secretaries of defense and published Monday asserting the U.S. military has no role in determining the outcome of the November 3 election still being contested by president Donald Trump.

The op-ed published in The Washington Post reminded federal officials and military officers they swore an oath "to support and defend the Constitution against all enemies, foreign and domestic. We did not swear it to an individual or a party."

It said "there's no role for the U.S. military in determining the outcome of a U.S. election" and ended with a plea to the Defense Department to ensure a peaceful and smooth transfer of power.

The letter was signed by former secretaries of defense Ashton Carter, Dick Cheney, William Cohen, Mark Esper, Robert Gates, Chuck Hagel, James Mattis, Leon Panetta, William Perry and Donald Rumsfeld. The terms of office of these former leaders spans the past 50 years.

From start to finish, the seemingly gargantuan effort to get all 10 of these men to read, agree to and sign the letter took place in the hours from New Year's Eve and New Year's Day, said Eric Edelman, the former Under Secretary of Defense for Policy under Bush.

A career foreign service officer, Edelman was also a former U.S. Ambassador to Turkey and Finland. He now serves as co-chair at the Bipartisan Policy Center, a Washington, D.C.-based think tank that promotes bipartisanship.

Edelman wrote and orchestrated the letter in consultation with Dick Cheney, Bush's vice president and himself a former secretary of defense. They were assisted by former State Department adviser Eliot Cohen, a famed political scientist and Dean of the Paul H. Nitze School of Advanced International Studies.

Edelman said Cheney told him he would sign the letter if he could get other former secretaries to do so. Edelman solicited the assistance of the Post and got all 10 secretaries to sign their names by Friday. Edelman said the motivation and timing for the letter was multifarious.

"There's the firing of Esper right after the election," said Edelman. "There's the installation of this cadre of political appointees around (acting Secretary of Defense Chris) Miller. There, there's the rush for the exit in Afghanistan."

Edelman also cited an attempt by the Trump administration to split U.S. Cyber Command and the National Security Agency last month. Then there was Trump's scandalous call with Georgia's secretary of state Brad Raffensperger on Saturday.

Edelman also said comments made by former national security adviser Michael Flynn about Trump invoking martial law to rerun the election in battleground states raised concerns among the former defense secretaries.