In the 1997 movie “Wag the Dog,” a fictional president starts a war abroad to distract from scandals at home.

“This is ‘Wag the Dog,’ except you start a war with the media,” a network source remarked to me.

Whatever this is, it’s just beginning. President Trump followed through on his threat about “banning” CNN, MS NOW and Politico this morning, as journalists for all three news outlets were turned away when they arrived to work at the White House.

On the long list of Trump administration actions against the media, this one shoots straight to the top, in terms of its scope and openly retaliatory intent.

National Review editor Philip Klein called it “an egregious violation of the principles of the free press” and “the most flagrant abuse of the modern era.”

All three news organizations signaled they will take legal action to defend the rights of their reporters. We’ll certainly be hearing more in the coming hours and days.

Bruce D. Brown, president of the Reporters Committee for Freedom of the Press, called Trump’s ban “flatly unconstitutional,” adding:

“The First Amendment is clear that once the White House invites in some journalists, it can’t ban others because it doesn’t like their reporting. This is textbook viewpoint discrimination and will be quickly struck down by the courts if challenged.”

Let’s walk through some of the other reactions and responses…

“Very broadly speaking, the mood among the press corps is concern and resignation, not really surprise,” a longtime White House correspondent told me just now.

I get that. Maybe today was inevitable: A day when Trump would finally say “get off my lawn,” not just to one correspondent, but to entire news divisions.

Here’s my full CNN.com story about what happened. First, MS NOW correspondent Akayla Gardner said that when she arrived at the White House, an officer “asked me to hand over my badge. He said that it was disabled. I asked why I was not able to get inside. He said it was above him.”

An hour or so later, CNN’s Betsy Klein was denied access. And then the same thing happened to Politico’s Cheyenne Haslett. Now a photo of Klein reporting live from outside the White House fence is leading the NYT homepage.

CNN said in a statement, “CNN’s mission to report on the U.S. government will continue regardless of any attempts to restrict physical access to the White House and other government buildings, or any other attempts to impede our journalism. We have a right under the U.S. Constitution to do our reporting without hindrance or interference from the government and this ban is an illegal assault on this fundamental right.”

If you’ve been watching CNN’s TV coverage today, you’ve probably heard me say that this episode is bigger than any single network. Yes, CNN is one of the outlets Trump is targeting, but I’d be sending out this special edition of Reliable Sources if ABC and Axios were the targets instead.

Because, let’s face it, they might be next. And they know it.

The White House Correspondents’ Association said it bluntly in a statement just now:

“Today’s action revoking access for journalists from CNN, POLITICO, and MSNOW violates the First Amendment. The implications extend beyond these organizations: a standard used to exclude one news outlet because of its coverage could be applied to any outlet in the future.”

More from the WHCA down below. Hour by hour, there’s a growing sense of solidarity among the American newsroom leaders who compete with each other for scoops, traffic and talent.

“We all see that a line has been crossed,” one top editor told me just now.

Trump said outright on Friday that he might bar other news organizations from entering what he started to call “my house,” before correcting himself and saying “people’s house.”

“There may be others to join them,” he said, at one point citing The New York Times and The Washington Post, calling both newspapers “crummy.”

The Post issued a statement this afternoon saying the president’s behavior “is a clear form of intimidation to silence coverage, stripping the public of information and threatening our democracy.”

The Times, too, spoke out and said the Trump administration’s ongoing anti-press push is, collectively, “an attempt to restrict Americans’ knowledge about their own government.”

More news outlets will be weighing in. I’m told by two sources familiar with the matter that the five major TV networks are actively discussing this issue. Here’s why that is significant…

CNN is one of five networks in the “TV pool,” which is the primary way people around the world see the president.

When Trump is on camera berating a reporter in the Oval Office, or boarding Air Force One, that’s the pool in action. Whichever network is on pool duty sends the video out to everyone — the other networks and many other news organization subscribers.

“And we know how much the president cares about television cameras,” anchor Kasie Hunt remarked during our breaking news coverage earlier today.

The work is expensive, highly technical, and would be very hard to replicate. The New York Post’s Steven Nelson explained it well in this story: “The ‘five families’ that operate that feed — whose number include ABC, CBS, NBC and Fox News — are particularly powerful in negotiating press access with Trump, who often demands network coverage of his comments.”

The TV pool rotation schedule is suddenly an issue now that CNN has been denied access to the White House.

A CNN team served as the TV pool for VP JD Vance’s trip to Iowa on Friday without incident.

CNN is scheduled to be the TV pool rep again on Monday when Trump travels to New York for the United Nations General Assembly.

So if CNN is prevented from fulfilling its pool duties, well, this becomes an even bigger deal.

My sense, from those aforementioned sources, is that there will be a show of solidarity among the major networks. So let’s talk about the Fox News angle…