When the government of Cambodia threatened on Monday to crack down on foreign news organizations that don’t “respect the state’s power,” it cited the example of the White House exclusion of several news outlets from a briefing. Cambodia was not the first country to take advantage of the new signals from the Trump White House.

In Russia, which has devoted huge resources to generating misinformation, the Foreign Ministry has adopted President Trump’s use of the term “fake news” for reports critical of him. The ministry has a new feature on its website in which articles critical of the government are stamped with a big red “FAKE.” In Turkey, where scores of journalists have been arrested and more than 150 media companies closed down, President Recep Tayyip Erdogan commended Mr. Trump for putting a CNN reporter “in his place” at a press conference by not taking his question and said such organizations “undermine national unity.”

The United States is still the greatest power with potentially the most formidable voice on earth, and the tweets and remarks of a new president are minutely followed everywhere not only for potential shifts in geopolitics, but also for the moral message. The autocrats of the world must be relieved to see how far Mr. Trump has wandered from Ronald Reagan’s “shining city upon a hill” and the America of John F. Kennedy, which commanded respect “not only for its strength, but for its civilization.”