This rare use of the dissent channel, a formal procedure for diplomats to protest U.S. policy straight to the State Department's leadership, comes as America's image suffers a blow from the violent scenes in Washington, where Trump encouraged his supporters to interrupt the symbolic vote in Congress that ratified his opponent Joe Biden's victory.
But they are not the only ones speaking up. A Trump appointee at the agency, Gabriel Noronha tweeted that Trump "needs to go" for fomenting "an insurrectionist mob that attacked the Capitol" and taking "every opportunity to obstruct the peaceful transfer of power."
Hours after those tweets, the White House fired Noronha, who was a special adviser to the special envoy for Iran and a department spokesperson.
He may not be alone in departing. Several senior Trump officials at the agency share his sentiments and were supportive of his tweets, another source told ABC News.
But there are less than two weeks in the Trump administration, and once Biden is inaugurated on Jan. 20, they will be forced to depart anyway.
For career diplomats in the Foreign Service, however, the damage to U.S. credibility will be a long-lasting challenge, especially as autocratic regimes have already deployed it to undermine American messages on human rights.
The cable directly confronts Trump for his remarks in front of the White House Wednesday, continuing to spread his false claims of widespread election fraud and urging his Vice President Mike Pence not to certify the electoral votes in Congress. A short time later, thousands of his rally's attendees descended on Capitol Hill and breached the building, threatening lawmakers and journalists and vandalizing the hallowed halls.
"After months of promoting baseless claims of voter fraud, which were rejected by the judiciary in dozens of cases, President Trump encouraged supporters, some armed, to march on the U.S. Capitol while Congress was certifying the results of a free and fair presidential election," the cable said, according to one source.
"His incitement led to a violent riot in the U.S. Capitol, five deaths, untold injuries, destruction and vandalism of government property, and incalculable damage to our democratic system and our image abroad," it continued.
In an internal message Wednesday, the State Department urged all embassies and consulates around the world to halt any public posts or statements, according to two sources -- a move that infuriated many diplomats who felt hamstrung by the silence that left them unable to push back on adversaries delighting in the scenes of chaos.
"Out of respect for the unacceptable events that occurred on January 6th at the Capitol, the Department took the prudent measure to temporarily pause planned social media activity," a State Department spokesperson confirmed to ABC News Friday.
That "pause" lasted for hours as the violent scenes unfolded, until Pompeo weighed in with a series of tweets Wednesday evening.
"Lawlessness and rioting -- here or around the world -- is always unacceptable," he said, calling for the rioters to "swiftly" face "justice." But he made no mention of his boss, fiercely protective of their relationship and loathe to show any sign of daylight between them.
The diplomats who signed the dissent cable said that Pompeo's response was not enough.
"The Department of State should explicitly denounce President Trump's role in this violent attack on the U.S. government. Just as we routinely denounce foreign leaders who use violence and intimidation to interfere in peaceful democratic processes and override the will of their voters, the Department's public statements about this episode should also mention President Trump by name. It is critical that we communicate to the world that in our system, no one -- not even the president -- is above the law or immune from public criticism," the cable said.
The State Department declined to comment on the cable, which was first reported by Foreign Policy magazine.
Pompeo met with Anthony Blinken on Friday, Biden's pick to succeed him as secretary. The first meeting between a Trump Cabinet chief and one of Biden's pick, it was originally scheduled to happen in December until Pompeo went into quarantine after being exposed to a person who tested positive for coronavirus.
"Today, I met with President-Elect @JoeBiden's Secretary-Designate @ABlinken in order to facilitate an orderly transition, and to ensure American interests are protected abroad," Pompeo tweeted -- the first time he's recognized Biden as "president-elect" in the two months since his victory was called and with less than 12 days left in that transition.
Pompeo faced criticism in November for saying the administration would ensure a "smooth transition to the second Trump administration" -- a prepared line that Trump later praised, but supporters said was a joke. He's also boosted Trump's false claims about widespread election fraud, without ever outright endorsing them.
The dissent cable sent Friday may have netted more signatures before it was sent, but not every diplomat is on board, particularly after the cable leaked to the media. All State Department cables are meant to be private, and some feared that by leaking it, the message becomes more political and damages the Foreign Service's nonpartisan nature.
At the same time, career diplomats started to speak out publicly Friday to defend the U.S. and cast Wednesday's violence as a dark day, but an example of how America must continually strive to be a strong democracy.
"America's democracy is not perfect, and the United States is not without fault," said U.S. ambassador to Uganda Natalie Brown, a career Foreign Service officer and a Black woman.
"But when we speak out against human rights abuses, we do so not because such abuses do not occur in America. When we speak out for press freedom, we do so not because American journalists are entirely free of harassment. When we call for judicial independence, we do so not because judges in America are free of external influence," she said in a statement. "On the contrary, we do so because we are mindful of the work still to be done in the American experiment with democracy and because our history has taught us that democracy must be defended if it is to endure."