“We must always have an unquestionable chain of command."

A group of retired U.S. military admirals and generals signed a letter released Tuesday questioning President Biden’s fitness for office and seemingly challenging the outcome of the 2020 presidential election.

The letter, signed by 124 former military leaders and posted by Flag Officers 4 America, said the “Constitutional Republic is lost” without “fair and honest elections that accurately reflect the will of the people.”

“Recent Democrat leadership’s inquiries about nuclear code procedures sends a dangerous national security signal to nuclear armed adversaries, raising the question about who is in charge,” the group added.

A group of retired U.S. military admirals and generals signed a letter released Tuesday questioning President Biden's fitness for office and seemingly challenging the outcome of the 2020 presidential election.

The letter, signed by 124 former military leaders and posted by Flag Officers 4 America, said the "Constitutional Republic is lost" without "fair and honest elections that accurately reflect the 'will of the people.'"

"The FBI and Supreme Court must act swiftly when election irregularities are surfaced and not ignore them as was done in 2020," the letter added.

Former Attorney General William Barr said in December the Justice Department uncovered no evidence of voter fraud that could have affected the outcome of the 2020 election, The Associated Press (AP) reported.

The signatories also questioned the "mental and physical condition of the Commander in Chief," adding that national security issues require quick and "accurate" decisions "involving life and limb."

"Recent Democrat leadership's inquiries about nuclear code procedures sends a dangerous national security signal to nuclear armed adversaries, raising the question about who is in charge," the letter said. "We must always have an unquestionable chain of command."

While in office, former President Trump periodically questioned Biden's mental capacity and age during the campaign season, at times referring to him as "sleepy Joe."

Kevin O'Connor, the president's doctor, released a report earlier this month maintaining that Biden is a "healthy, vigorous, 77-year-old male, who is fit to successfully execute the duties of the Presidency," Business Insider reported.

The signatories additionally compared potential challenges to ideological battles not seen since America's founding.

"We are in a fight for our survival as a Constitutional Republic like no other time since our founding in 1776," they said. "The conflict is between supporters of Socialism and Marxism vs. supporters of Constitutional freedom and liberty."

A statement on the Flag Officers 4 America website, says that although its members are no longer engaged in active military service, they are "bound by that oath to do what we can, in our capacity today, to protect our nation from the threats to her freedom."