Retired Lt. Col. Alexander Vindman, who rose to national prominence during Donald Trump’s first impeachment trial, filed a civil lawsuit on Wednesday against the former president’s son, Don Jr., and Trump associates Rudy Giuliani, Dan Scavino and Julia Hahn.

The lawsuit contends:

In late 2019 and early 2020, President Trump and [the defendants] engaged in an intentional, concerted campaign of unlawful intimidation and retaliation against a sitting Director of the National Security Council and decorated military officer, Lieutenant Colonel Alexander Vindman, to prevent him from and then punish him for testifying truthfully before Congress during impeachment proceedings against President Trump.

Vindman told Congress that he heard Trump pressure the Ukrainian president to find damaging information on his chief political rival, Joe Biden. Vindman’s lawsuit alleges that he was unfairly maligned because of his disclosure, which ultimately contributed to Trump’s first impeachment.

More from the filing:

Defendants’ attacks on Lt. Col. Vindman were specifically tailored to falsely paint him as disloyal to the United States, engaged in “espionage,” and a politically motivated “leftist” within the military who was insubordinate and even broke the law.

Defendants’ campaign against Lt. Col. Vindman was designed to inflict maximum damage by creating and spreading disinformation that they knew would be picked up and amplified by anchors at Fox News, other right-wing media outlets, and across social media—all while Lt. Col. Vindman’s active duty status prevented him from effectively defending himself.

In an op-ed for USA Today, Vindman says his decision to testify against Trump cost him his career and led to threats against his family.

“Public servants who do their duty, tell the truth and uphold their oaths of office shouldn’t be subjected to intimidation and retaliation. I’ve been disheartened to see so little accountability for what I experienced and other abuses of power that took place during that time. I worry about what that means for future whistleblowers, regardless of issue or party, who also want to do the right thing,” Vindman wrote.

He continued: “That’s why I filed a lawsuit Wednesday against several of the close associates and allies of former President Trump who participated in a concerted effort to falsely attack my loyalty to the United States and punish me for testifying, including by abruptly removing me and my twin brother from the White House and temporarily blocking my promotion within the Army.”

“Sharp-elbowed politics is not against the law, nor should it be,” Vindman wrote. “It has always been fair game to criticize public figures. But what happened to me was something different. I was attacked in a way calculated to inflict maximum personal and professional damage likely in order to prevent me from testifying or to punish me for doing so. In this country, that violates the law.”

Vindman framed his lawsuit against the Trump associates as an attempt to stop them from eroding democracy, writing, “Only now are we starting to gain a fuller picture of some of the abuses that occurred during the Trump administration. And only now are we starting to see the beginnings of a serious effort at accountability. Yet Trump and his allies continue to resist these efforts, having been emboldened by years without consequences. So I’ve decided again to take a stand on behalf of what is right. Failing to do so might invite more abuses of power and a deeper slide into authoritarianism.”

ABC News reports:

The suit claims that the message sent to Vindman “reverberates to this day, as witnesses subpoenaed by Congress in connection with its investigation into the events of January 6, 2021, continue to heed former President Trump’s instructions to defy those subpoenas, undermining Congress’s constitutional oversight role and the fundamental principle of checks and balances between three co-equal branches of government.”

“Vindman is asking a federal judge to rule that Trump Jr., Giuliani, Scavino and Hahn all engaged in the conspiracy campaign, and to award him financial damages in an amount that would be determined after trial,” ABC News adds.

Business Insider explains:

The civil suit accuses the defendants of violating the Ku Klux Klan Act of 1871, which among other things prohibits conspiracies to prevent someone from holding or discharging the duties of their office, or to retaliate against them for doing so. It also bars conspiracies to stop witnesses from testifying or to retaliate against them for doing so.