Boston: A California man has been charged with threatening to kill employees of the Boston Globe newspaper in retaliation for its role in leading an editorial defence of press freedoms by hundreds of US news organisations against attacks by US President Donald Trump.

Federal prosecutors said Robert Chain, 68, called journalists "the enemy of the people" in threatening telephone calls that echoed the phrase Trump has used to criticise unflattering news coverage through his campaign and time in office.

FBI agents remove evidence from the home of Robert Chain in the Encino, Los Angeles, on Thursday. Credit:LA Daily News/AP

"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," Andrew Lelling, the US attorney for Massachusetts and a Trump appointee, said in a statement on the arrest.

About two dozen federal agents in tactical gear and an armoured vehicle arrived at Chain's stucco single-storey home in Los Angeles' Encino section just before 6am. Neighbours said they heard small explosions, like the bursting of flash-bang grenades, before Chain was led from his house dressed only in a pair of shorts.