California (CNN Business) President Trump's years-long effort to punish CNN for its news coverage took a new, yet wholly unsurprising turn on Monday when he suggested a boycott of CNN's parent company AT&T.

The idea, according to Trump's tweets, is that if enough people cancelled their AT&T subscriptions, "they would be forced to make big changes at CNN."

The reaction fromamounted to a shrug. The company declined to comment on Trump's provocation. The stock surged in early trading and closed up 1.67% for the day.

As is so often the case in the Trump years, his tweets shattered norms but were not taken very seriously. As a presidential candidate he called for a boycott of Apple . Nothing came of it. No one really even remembers it.

The same result is likely in this case.

AT&T executives expected that Trump would single out the company for its ownership of CNN at some point, according to a source familiar with the matter. So Monday's tweets were not startling. And there were no signs that customers were abandoning AT&T on Trump's signal.

When the president landed in the United Kingdom for his state visit on Monday, he said he didn't like what he saw when he tuned into CNN.

He repeated a complaint he has lodged in the past: That CNN has a dominant worldwide footprint, informing people around the world about American politics.

"The only problem is that @CNN is the primary source of news available from the U.S. After watching it for a short while, I turned it off," he tweeted . "All negative & so much Fake News, very bad for U.S. Big ratings drop. Why doesn't owner @ATT do something?"

AT&T pledged to respect and protect CNN's editorial independence when it first sought to acquire Time Warner weeks before the presidential election in 2016.

Trump's Justice Department sued to block the deal , and AT&T prevailed after a protracted court fight. The DOJ steadfastly denied that the suit was politically motivated. But Trump made no secret about his ill will towards CNN.

Trump's current Attorney General William Barr, who was a member of Time Warner's board of directors at the time of the trial, even questioned the motives behind the administration's suit.

Before the trial, Barr submitted an affidavit in which he expressed discomfort with the administration's position on the merger, saying it was a "product not of well-versed substantive analysis, but rather political or other motivation."

The deal took effect last summer. Time Warner was renamed WarnerMedia. AT&T has now owned CNN for almost a year, and CEO Randall Stephenson has renewed his pledge not to meddle at the news network.

Meddling, it seems, is what Trump wants.

"I believe that if people stoped using or subscribing to @ATT, they would be forced to make big changes at @CNN," he tweeted. Then took a jab at the network's ratings.

One of the Democratic candidates for president, Amy Klobuchar, called out Trump for his conduct.

"The President is on foreign soil advocating boycotting an American company because the press isn't covering him favorably. Un-be-lievable," Klobuchar wrote.

Peter Baker, a veteran White House correspondent for The New York Times, also pointed out how unusual it is.

"The president of the United States just called for an economic boycott of one of the country's largest telecommunications firm as a way of pressuring a media organization to cover him in a way that he approves of," he tweeted

PEN America, an organization that represents writers and journalists and is suing Trump on First Amendment grounds, said his boycott suggestion "makes plain the self-serving, insidious nature of his attacks on the media and his total disregard for the principle of press freedom."