The Trump administration is plainly upset with the behavior of a certain CNN reporter. But how far is it willing to go to make its case that the reporter acted improperly during a news conference with President Trump?

One answer emerged Wednesday night when White House press secretary Sarah Sanders tweeted a video of the episode, involving CNN’s Jim Acosta, the network’s chief White House correspondent. Experts said the video, in which Acosta is seen rebuffing a press aide’s attempt to take a microphone out of his hands, was altered to exaggerate the aggressiveness of Acosta’s actions.

If that is the case, the video may belong in a category rarely employed by democratic governments: visual propaganda.

The White House video, apparently made by a contributor to the conspiracy-peddling website Infowars , speeds up the movement of Acosta’s arms as the unidentified aide grabs at the mic during a heated conversation between the reporter and Trump. The video tweeted by Sanders also eliminated Acosta’s comment to the young woman — “Pardon me, ma’am” — as he sought to continue questioning the president.

On Thursday, Sanders offered no apologies. “The question is: Did the reporter make contact or not?” she asked reporters a day after the White House revoked Acosta’s press credentials for his alleged transgression. “The video is clear, he did. We stand by our statement.”

The White House’s actions and account of them has drawn widespread condemnation, particularly from journalists and news organizations. The White House News Photographers Association, among others, said it was appalled by Sanders’s video.

“As visual journalists, we know that manipulating images is manipulating truth,” said the group’s president, Whitney Shefte, a Washington Post videographer. “It’s deceptive, dangerous and unethical. Knowingly sharing manipulated images is equally problematic, particularly when the person sharing them is a representative of our country’s highest office with vast influence over public opinion.”

Totalitarian governments have long recognized the value of altering photos and videos to manipulate public opinion and perception. Officials were regularly airbrushed out of state photos in the Soviet Union as dictators such as Joseph Stalin purged internal enemies. Wartime governments regularly censor images or release them selectively to maintain popular order and morale.

Modern-day regimes vigorously employ digital techniques to fool viewers; North Korea’s propaganda ministry routinely alters images emanating from the isolated nation, from photos of leader Kim Jong Un’s ears to state-issued pictures of the country’s military prowess.

Such tactics have been irregularly employed in democracies like the United States, too. Political campaigns are rife with fake images. During his red-baiting campaign of the early 1950s, Sen. Joseph R. McCarthy (R-Wis.) distributed doctored photos of his opponents to suggest communist sympathies, according to Boston University journalism professor Christopher Daly. One “composite” photograph appeared to show Sen. Millard Tydings (D-Md.) deep in conversation with the head of the American Communist Party.

One of the most notorious instances of deliberate image ma­nipu­la­tion by the White House, said Daly, was its presentation of photos of the Gulf of Tonkin incident in 1964. The photos, apparently showing a minor naval skirmish, helped persuade Congress to pass a resolution granting President Lyndon B. Johnson the authority to provide greater military assistance to the government of South Vietnam.

News organizations disapprove of altering photos and videos, on the premise that doing so deceives readers and viewers. News photos are cropped to better frame the action in them, and videos are edited to enhance clarity and storytelling — all considered legitimate practices. But some images are unethically altered. Judges in the annual World Press Photo competition have regularly disqualified entries because of “excessive” post-processing, such as toning that removes or hides objects in a photo.

Among the most infamous examples of news-photo ma­nipu­la­tion were National Geographic’s shot of the Egyptian pyramids, “squeezed” together to fit on the magazine’s cover in 1982, and Time magazine’s cover image of O.J. Simpson in 1994. Time darkened Simpson’s image, making him look more sinister and menacing.

While Sanders’s Acosta tweet doesn’t rise to Gulf of Tonkin levels, it raises several troubling questions, said Emmett Sullivan, who lectures in modern history and imagemaking at the University of London. He said that the video she distributed is identical to one by Paul Joseph Watson, a conspiracy theorist affiliated with Alex Jones’ Infowars site.

“The issue is then not one of manipulation, but simply judgment in sourcing your information,” said Sullivan. “Why not use the C-SPAN feed directly? America can expect the president’s press secretary to cite the best sources, and Sarah Sanders has failed the American people here.”

In a tweet on Thursday, Watson disputed that his video was altered: “The media, with zero fact checking, launched a conspiracy claiming I ‘sped up’ or ‘doctored’ the Jim Acosta video so they could distract from Acosta’s behavior. This is false. I did not ‘doctor’ or ‘speed up’ anything. It was all fake news.”

Acosta, who has tangled often with the White House and Trump, tweeted that Sanders’s claim that he put his hands on the press aide was “a lie.”

Sullivan says governments are less likely than ever to knowingly pass off a fake. The reason: “It is simply too easy for the manipulation to be spotted now. It generates too much adverse publicity in the media and social media precisely because video is such a common medium of communication.”

Then again, technology has created a kind of “arms race” between tools that permit video and photo ma­nipu­la­tion and those designed to sniff out the fakes, said Hany Farid, a professor of computer science at Dartmouth College.

“Obviously releasing misleading or doctored information is problematic, particularly when done by our officials,” he said. But as the technology advances, he said, the question of what’s real and what’s not may be up for debate. “As the technology that allows us to manipulate images gets more sophisticated and easier to use, then the claim that a video is fake becomes more credible,” he said.

Farid points to another infamous piece of video to illustrate his point, the “Access Hollywood” tape of Trump bragging about forcibly kissing and groping women. When that recording was revealed in 2016, he said, “nobody said it was fake.” Since then, Trump has cast doubt on its authenticity.

“If that recording broke today, he would’ve almost certainly say it is fake,” he said. And given the spread of digital-altering technology, he “would have had plausible deniability.”