New York Times media columnist Jim Rutenberg's recent dispatch from Moscow contains a litany of alarming observations about the Russian media.

“As soon as I turned on a television here I wondered if I had arrived through an alt-right wormhole,” Rutenberg wrote in Monday's newspaper.

But the most significant observation might have been about the American press and its credibility in Russia — or lack thereof, as President Trump keeps up his sustained campaign against what he calls the “fake news media.”

Rutenberg noted that in Russia, Syria's most powerful ally, Trump's broadsides against U.S. news outlets are being used to dismiss reports that Syrian President Bashar al-Assad deployed chemical weapons against his own citizens earlier this month:

When Trump administration officials tried to counter Russia’s “false narratives” by releasing to reporters a declassified report detailing Syria’s chemical weapons stockpiles — and suggesting to the Associated Press without proof that Russia knew of Mr. Assad’s plans to use chemical weapons in advance — the Russians had a ready answer borrowed from Mr. Trump himself.

As the pro-Kremlin newspaper Izvestia put it, “Apparently it was for good reason Donald Trump called unverified information in the mass media one of the main problems in the U.S.”

It was the best evidence I’ve seen of the folly of Mr. Trump’s anti-press approach. You can’t spend more than a year attacking the credibility of the “dishonest media” and then expect to use its journalism as support for your position during an international crisis — at least not with any success.

Trump appears not to have considered the real cost of his “fake news” accusations. When there is an international dispute — as there is between the United States and Russia over who was behind the chemical attack in Syria — it is in the president's best interest for the reporting of U.S. news outlets to be regarded as legitimate on the world stage. Yet Trump claims constantly that The Washington Post, New York Times, CNN and others are not to be believed.

Trump's antagonism toward the press hurts him in other ways, too. Last week, for example, the White House issued a two-sentence, information-starved summary of a phone call between Trump and Chinese President Xi Jinping. China, meanwhile, issued a 14-paragraph statement describing its version of the conversation.

Trump and his aides probably thought they were sticking it to the media by withholding details of the call. What they really accomplished, however, was empowering China to dictate the public narrative.

Also last week, Secretary of State Rex Tillerson mostly avoided reporters on a visit to Moscow, in keeping with his previously stated position that “all of the things we're going to do, you will know them after they’ve happened.” Because Tillerson's team refused to keep U.S. journalists up to date throughout the visit, Russia was in control.

At one point, the Associated Press reported a Kremlin claim that the United States and Russia had agreed on the need for a United Nations investigation of the use of chemical weapons in Syria. An hour and 43 minutes passed before the State Department told the AP that there was no such agreement.

Stonewalling and demonizing the media was an effective campaign tactic for Trump. It still fires up his base. But it can create foreign-policy headaches, too.