President Donald Trump defended himself against allegations that he made an improper request of a foreign leader at the White House Wednesday by continuing to attack the whistleblower who made them.

“This country has to find out who this person was, because that person’s a spy, in my opinion,” the president said during an Oval Office press conference with the president of Finland, arguing only “legitimate” whistleblowers ought to be protected by whistleblower laws.

Many of the president’s latest attacks have taken this form, marking an evolution from his early attempts to discredit the whistleblower’s allegations to more pointed and personal attacks on the whistleblower himself and his anonymity.

In the course of his attacks, the president has also attempted to cast doubt on the impeachment inquiry the allegations have led to in the House of Representatives. Now his critics argue his threats could have a chilling effect — as well as potentially endangering the whistleblower.

Trump’s claims about the whistleblower’s illegitimacy have no provable connection to reality. But experts say there are real fears his actions will keep federal employees from speaking out about future acts of concern, in large part because while there are measures in federal law meant to negate retaliation against whistleblowers, they do not apply to the president.

Trump has worked to seed doubt about the whistleblower’s accuracy — and the whistleblowing process

Following the first news reports about the whistleblower’s complaint in early September, Trump referred to the official as “highly partisan” and a “so-called whistleblower” on Twitter. But after the complaint was made public, the president began a more nuanced attack: casting doubt on the whistleblower’s accuracy.

The whistleblower’s complaint states he sourced his allegations from a number of federal officials with firsthand knowledge of a conversation Trump had with Ukrainian President Volodymyr Zelensky, but he admits he was not himself on the call. The inspector general took this into account and conducted his own investigation into the allegations, deemed the complaint credible, of great import, and eventually told Congress members it “relates to one of the most significant and important of the [director of national intelligence’s] responsibilities to the American people.”

Trump’s own administration has complicated the president’s argument by releasing a memo summarizing his call with Zelensky that confirms the central allegation contained in the complaint.

But Trump, nevertheless, has attempted to frame the allegations as little more than gossip, saying they are “all second hand information that proved to be so inaccurate.”

He’s also impugned not just the whistleblower’s information, but the entire whistleblower process.

Following the publication of an article by conservative outlet that incorrectly claimed intelligence officials had changed whistleblowing regulations shortly before the Ukraine whistleblower filed his complaint, Trump tweeted Monday, “WHO CHANGED THE LONG STANDING WHISTLEBLOWER RULES ... ?”

This rule change did not happen, as national security lawyer and whistleblower expert Brad Moss explained to Vox: “The law doesn’t prohibit [secondhand information] — in fact the laws have never prohibited that, when it comes to the initial whistleblower.”

The president’s tweet, and the article, led the intelligence community inspector general to release a statement Monday afternoon that reaffirmed the inspector general did not, and cannot change the law, and that read in part, “In fact, by law the Complainant ... need not possess first-hand information in order to file a complaint or information with respect to an urgent concern.”

Nevertheless, the president and his allies have seized upon the rule change conspiracy theory to make the whistleblowing process seem rigged against him. And by impugning the process, they work to cheapen it — to say that if the rules governing it are mutable, then perhaps the facts presented in a complaint are less than solid as well.

All of this has prefaced the president’s latest attacks against the whistleblower, and the ones his critics see as most dangerous: An assault not just against the whistleblower’s information or the process, but against the man personally.

Critics fear Trump will have a chilling effect on whistleblowing

Trump has made it clear he wants to know the whistleblower’s identity and Wednesday branded him “a spy.” He had previously told US staffers at the UN that whoever gave the whistleblower the information he used to compile his complaint was “almost a spy.” And the president suggested that the US ought to think about reviving its old practice of executing spies.

This sort of rhetoric has Democrats and experts concerned Trump’s demands could endanger the whistleblower are doing real damage to the whistleblower system as a whole.

On Wednesday, House Intelligence Committee Chair Adam Schiff — one of the leaders of the investigation into the whistleblower’s allegations — told reporters at a press conference that suggestions the whistleblower and his sources are “somehow treasonous and should be treated as traitors and spies” were “a blatant effort to intimidate witnesses.” He also called such comments “an incitement to violence.”

It is clear those who have alleged wrongdoing on the part of the president have faced physical violence in the past. Democrat and frequent Trump foil Rep. Ilhan Omar has spoken of a number of deaths threats she has received, for instance, and Cesar Sayoc was sentenced to 20 years in prison for mailing pipe bombs to some of Trump’s critics. Should the whistleblower’s name become public, he could face similar threats.

Previously, Schiff has argued dangers go beyond one individual, arguing the president is working towards the “complete breakdown of the whistleblower system and it intimidates other whistleblowers from coming forward.”

In response to Trump’s words, Democrats on the House Intelligence Committee have put forward a resolution demanding Trump and his allies “immediately must cease their public efforts to discredit the Whistleblower, as well as others who may have knowledge with respect to the allegations contained in the Complaint.”

Experts have raised similar concerns. “Any federal employee who hears the reaction from the White House will think, ‘If I blow the whistle, I will likely be subject to a personal attack,’” whistleblower lawyer and former Obama administration official Jason Zuckerman told the Washington Post.

Even Republican Sen. Chuck Grassley, who has pushed the president’s talking points previously, called for levelheadedness on Tuesday, “This person appears to have followed the whistleblower protection laws and ought to be heard out and protected. We should always work to respect whistleblowers’ requests for confidentiality.”

Trump is unlikely to be bothered by this subtle rebuke from Grassley. In fact, disregarding presidential norms by requesting Ukraine investigate Biden got the president into this mess. What worries some observers is that the president is completely within his powers to demand the identity of the whistleblower, and to call for retribution against him.

Whistleblower law is designed to protect people who make complaints — but not from the president

On Tuesday, Trump asked on Twitter, “Why aren’t we entitled to interview & learn everything about the Whistleblower, and also the person who gave all of the false information to him.”

In general, the reason why is the law.

The Intelligence Authorization Act states:

No action constituting a reprisal, or threat of reprisal, for making such complaint or disclosing such information to the Inspector General may be taken by any employee in a position to take such actions, unless the complaint was made or the information was disclosed with the knowledge that it was false or with willful disregard for its truth or falsity.

Other regulations expand on these protections, like Presidential Policy Directive 19, which (among other things) states a whistleblower with access to classified information cannot have that access revoked in retribution for making a complaint. And the Inspector General Act of 1978 explains a whistleblower’s identity must be protected should they choose to stay anonymous (unless the inspector general’s investigation into the complaint requires it be revealed).

All of these protections are granted to a whistleblower, national security lawyer Brad Moss told Vox, as long as they “adhere to the strict parameters of what the law permits you to do, and not go beyond it.”

The Ukraine whistleblower did all of these things, following the guidelines laid out in the law. Should he have done otherwise — say, by leaking his complaint to the press — Moss said, “the law cannot protect you.”

There is one issue with the law, however: It doesn’t seem to apply to the president.

“There really isn’t much to stop Donald Trump from ordering the disclosure of the identity of the whistleblower,” Moss said. “He himself is arguably beyond the scope of the legal restrictions. ... Any of those normal provisions don’t really apply to the president because the president is the head of the executive branch ... so it’s unlikely there’s any viable legal recourse that could be taken in that situation. The only recourse that is envisioned is political, and it’s namely impeachment.”

This places the Ukraine whistleblower — and any whistleblower — at risk. If Trump ordered his intelligence community inspector general to tell him the identity of the whistleblower, the inspector general would have to do so. And Trump could then tweet the whistleblower’s name, opening him up to all manner of harassment, and perhaps even physical danger.

It is unclear whether Trump is seriously considering ordering those in his administration aware of the whistleblower’s identity to reveal it. The whistleblower would likely hope the president respects his legal protections, although Trump is under no requirement to do so.

Ordinarily, a president might be expected to do everything in their power to protect a whistleblower, but Trump has never been one for presidential norms — in fact, disregarding them on his call with Zelensky is part of how he arrived at this political moment.