More than 120 retired generals and admirals have signed a letter saying that the U.S. is in "deep peril" under the leadership of President Joe Biden, specifically warning that the mental condition of the nation's oldest commander in chief "cannot be ignored."

What are the details?

The letter was released by Flag Officers 4 America, and was signed by 124 retired "military officers entitled to carry a flag indicating their rank," The Daily Caller noted.

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

The retired military leaders went on to say that "without fair and honest elections that accurately reflect the 'will of the people' our Constitutional Republic is lost," saying that "aside from the election, the Current Administration has launched a full-blown assault on our Constitutional rights in a dictatorial manner, bypassing the Congress, with more than 50 Executive Orders quickly signed."

At the end of a long list of bullet points citing "additional national security issues and actions," Flag Officers 4 America wrote:

"The mental and physical condition of the Commander in Chief cannot be ignored. He must be able to quickly make accurate national security decisions involving life and limb anywhere, day or night. 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. We must always have an unquestionable chain of command."

The officials ended the letter with a call for action, urging "all citizens to get involved now at the local, state and/or national level to elect political representatives who will act to Save America, our Constitutional Republic, and hold those currently in office accountable," concluding, "The 'will of the people' must be heard and followed."

Biden, 78, is the oldest American president to ever be elected, and he faced questions from opponents during both the Democratic primary and the general election over his mental fitness for office.

A White House spokesperson told People magazine on Wednesday that Biden "is planning to have a checkup later this year, and the results will be made public."

The outlet noted that White House Press Secretary Jen Psaki told reporters last week that the administration "will be transparent" to reporters about the results of Biden's first physical when it happens.

People further reported that "Biden similarly promised during the 2020 campaign to be 'totally transparent in terms of my health.'"