The front page of the Thursday, August 16, 2018 edition of the Boston Globe newspaper reads "Journalists are Not the Enemy" as it sits for sale on August 16, 2018 in Cambridge, Massachusetts.

A man was charged on Thursday with threatening to kill employees of The Boston Globe after the paper's decision to coordinate a national response to President Donald Trump's attacks on the media, according to a release issued by the Justice Department.

In more than a dozen phone calls to the newspaper, Robert Chain, 68, allegedly threatened to kill Globe employees and referred to the publication as "the enemy of the people," according to the release. The threats started Aug. 10, the day the Globe announced that it would be coordinating editorials from papers around the country to "protect free press from Trump attacks."

More than 300 publications published editorials on Aug. 16 as part of the project, according to a tally from the Globe. That day, Chain allegedly threatened to shoot Globe employees in the head.

"You're the enemy of the people, and we're going to kill every one of you," Chain allegedly said in that phone call, adding an expletive, according to a transcript obtained by NBC News. Chain referred to special counsel Robert Mueller, asking: "Why don't you call Mueller, maybe he can help you out buddy."

Chain, of Encino, California, was arrested Thursday and eventually will be transferred to Boston. He is expected to appear in federal court in Los Angeles on Thursday afternoon.

Trump has repeatedly referred to the press as the enemy of the people, transforming "Fake News!" into a political slogan and conservative rallying cry. During his campaign and later as president, Trump has targeted journalists at political rallies, and cultivated anger against reporters. In particular, the president has gone after what he calls the "failing" New York Times, CNN and Jeff Bezos, the billionaire owner of The Washington Post.

Just hours before the announcement of Chain's arrest, Trump wrote in a post on Twitter that he could not "state strongly enough how totally dishonest much of the Media is."

He signed off the tweet: "Enemy of the People!"

Trump tweet

In a statement, Andrew Lelling, U.S. attorney for the District of Massachusetts, a Trump appointee, said that anyone "who puts others in fear for their lives" will be prosecuted regardless of political affiliation.

"In a time of increasing political polarization, and amid the increasing incidence of mass shootings, members of the public must police their own political rhetoric," he said. "Or we will."

Chain is charged with one count of making threatening communications in interstate commerce, and could face up to five years in prison, one year of supervised release and a fine of $250,000, the Justice Department said. The case is being prosecuted by Assistant U.S. Attorney George Varghese.

Jane Bowman, a spokesperson for the Globe, said in a statement that the newspaper was grateful for the work that law enforcement did to protect the newspaper while the threats came in, for investigating the source of the threats, and for Thursday's arrest. She said the paper could not have asked for a stronger response.

"While it was unsettling for many of our staffers to be threatened in such a way, nobody – really, nobody – let it get in the way of the important work of this institution," Bowman said.

The White House did not immediately respond to a request for comment from CNBC.