FBI says Robert Chain began a series of threatening calls after the newspaper announced it was coordinating a response to Trump’s attacks on the media

A man has been arrested and charged with threatening to kill employees of the Boston Globe newspaper, in messages repeating Donald Trump’s claims that journalists are the “enemy of the people” and “fake news”.

Robert Chain called the Globe’s newsroom and claimed he would shoot staff members in the head, according to the FBI, which said Chain later specified that he was retaliating against the newspaper’s criticism of Trump’s attacks on the news media.

Chain, of Encino, California, owns several firearms and was found to have purchased a new 9mm carbine rifle in May this year, according to US authorities.

Andrew Lelling, the US attorney for Massachusetts, said in a statement: “In a time of increasing political polarisation, and amid the increasing incidence of mass shootings, members of the public must police their own political rhetoric. Or we will.”

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Chain, 68, is due to appear in a federal court in Los Angeles on Thursday afternoon charged with making threatening communications in interstate commerce. He will later be transferred to Boston, officials said.

In an affidavit filed to federal court in Boston, the FBI said Chain began a series of 14 threatening calls to the Globe soon after the newspaper announced on 10 August that it was coordinating a response by US publications to Trump’s attacks. Dozens of outlets agreed to publish editorial columns on the subject on 16 August.

Trump has led an unprecedented assault on the American media over the past three years, falsely claiming that coverage unfavourable to him is “fake news” and declaring journalists to be enemies of the public. He has frequently urged supporters at rallies to direct abuse at individual reporters, leading some to hire bodyguards.

Chain allegedly called the Globe from a blocked number on 16 August and said: “You’re the enemy of the people, and we’re going to kill every fucking one of you.” After suggesting that staff call special counsel Robert Mueller for help, Chain allegedly said: “I’m going to shoot you in the fucking head later today, at four o’clock.” Telephone records traced the call back to Chain’s home landline, the FBI said.

That morning, Trump had posted several attacks on the media to Twitter, complaining about “fake news” and declaring that the media was “opposition party” and “very bad for our great country”.

The FBI said Chain’s calls scared employees of the Globe, leading the newspaper to call police and contract a private security company to protect its staff.

Six days later, Chain allegedly called the newspaper from a cellphone registered to his wife. When asked by a Globe employee why he was calling, Chain allegedly said: “Because you are the enemy of the people.”

Chain allegedly continued: “As long as you keep attacking the president, the duly elected president of the United States, in the continuation of your treasonous and seditious acts, I will continue to threat, harass, and annoy the Boston Globe, owned by the New York Times, the other fake news.”

The New York Times Company previously owned the Boston Globe but sold the newspaper in 2013. Trump, apparently angered by the coordinated editorials against him, drew attention the link between the two newspapers in a tweet on 16 August.

Following the charge against Chain, the Committee to Protect Journalists (CPJ), which advocates for press freedom, said that amid a “hostile climate” newsrooms and law enforcement must take threats against reporters seriously.

“Journalists should never face violence for doing their jobs,” said Alexandra Ellerbeck, the CPJ’s north America program coordinator.

The president continued to attack the media using the same terms on Thursday, a day after his own justice department filed its complaint to court detailing Chain’s use of Trump’s slogan. Trump claimed in a tweet that he “cannot state strongly enough how totally dishonest much of the Media is,” adding: “Enemy of the People!”