Federal officials on Wednesday arrested several alleged members of a white-supremacist group called Atomwaffen Division, including its two leaders, accusing them of plotting to intimidate journalists by calling police to their homes and offices and dropping off threatening fliers.

John Cameron Denton, of Montgomery, Tex., is charged in U.S. District Court in Alexandria with conspiring to call in fake threats targeting a ProPublica reporter and his office. Police arrived in force at both locations, at one point briefly detaining the reporter.

In federal court in Seattle, prosecutors say Kaleb Cole and three others hatched a different intimidation plan: finding out where journalists live and leaving posters at their homes with messages featuring swastikas, weapons and the vague threat that they were being watched.

After Atomwaffen founder Brandon Russell was arrested in Florida in 2017, according to prosecutors, Denton and Cole, of Arlington, Wash., took leadership of the group. As news organizations began to expose their members, authorities said they discussed how to strike back.

“We must simply approach them with nothing but pure aggression,” Cole said in a recorded message in 2018, according to court records. “We cannot let them think they are safe.”

Denton, according to prosecutors, directed a group of neo-Nazis who harassed ProPublica and a reporter there by calling in fake threats to law enforcement in hopes of provoking an overwhelming response — a practice known as “swatting.” While the reporter is not named in court papers, the description is of A.C. Thompson, who has written extensively about Denton and Atomwaffen.

The group called New York police to ProPublica’s office in December 2018, according to the criminal complaint, claiming that there was a pipe bomb, a hostage and a dead body inside.

A dozen officers responded and cleared the floor in question; one employee was there and “visibly shaken,” according to the complaint.

Two months later, prosecutors say the group called police to Thompson’s home in California, claiming that he was armed and had just killed his wife. He and his wife were briefly detained by police.

According to the complaint, Denton acknowledged his role in an interview with an undercover agent last month.

In Seattle, prosecutors say Cole and a high-ranking recruiter named Cameron Brandon Shea came up with “Operation Erste Saule,” a German term they used to refer to the news media. One person involved recommended using the Society of Professional Journalists website to pick targets, according to court papers. Employees of the Anti-Defamation League, a Jewish organization that tracks anti-Semitism and has investigated Atomwaffen, reported receiving threatening messages.

“You have been visited by your local Nazis,” the messages read. “Your actions have conse­quences.”

Prosecutors say an Atomwaffen member named Johnny Roman Garza participated in the intimidation by leaving fliers at the homes of black and Jewish journalists in Arizona, while Taylor Ashley Park-Dipeppe is accused of attempting to threaten a reporter in Florida. However, prosecutors say he left the poster at the wrong address.

The FBI, already monitoring the group, says it warned many targets in advance.

The arrested men were ordered held after their first appearances in court Wednesday. Attorneys had not yet been assigned to their cases.

The FBI in recent months has seemed to take an aggressive posture toward white-supremacist organizations. Last month, agents arrested several members of a group called the Base, including some it feared could unleash violence at a Virginia gun rights rally. Jill Sanborn, FBI assistant director for counterterrorism, said the Atomwaffen case “serves as a warning to anyone who intends to use violence as intimidation or coercion to further their ideology that the FBI remains steadfast in our commitment to protect Americans from domestic terrorism.”

John William Kirby Kelley, a 19-year-old former student at Old Dominion University, was charged in the swatting conspiracy last month. He was identified after the group called in a fake threat at the school, according to court records, and he then accidentally called school authorities again using his listed phone number.

The group kept a long list of targets, including many public officials and journalists, on a website called Doxbin, according to prosecutors. More than 100 such calls were made, according to prosecutors.

The same Google Voice number was used to call in fake threats on a Cabinet official who lives in Alexandria, the Alfred Street Baptist Church, ODU, ProPublica’s office and Thompson, according to law enforcement.

The Cabinet official is not named, but a list of the group’s targets includes Kirstjen Nielsen, who at the time was the homeland security secretary and who lives in Alexandria. A person familiar with the case said that when 911 was called to her home last year, police consulted with the Secret Service and no action was taken.

Another victim on the list was Pulitzer Prize-winning newspaper columnist Leonard G. Pitts Jr. He was ordered out of his home and handcuffed by police after a false report made in June.

AFDL first identified Denton as an Atomwaffen leader in 2018. ProPublica subsequently reported that Denton, under the code name “Rape,” was in charge of the group, designing its recruitment, training and promotional materials.

According to the ADL, Atomwaffen got its start among young members of an online extremist forum who wanted to take real-life action. Atomwaffen has been linked to at least five killings across the country.

The group promotes what is called “accelerationist” philosophy: the belief that neo-Nazis should engage in atrocities to spur the collapse of society and a race war in which white people will come out on top.

“This particular community brought together white supremacists who had similar backgrounds — young . . . struggles with depression, anxiety and suicide,” senior ADL researcher Joanna Mendelson said.

Though violent, Atomwaffen was never large, Mendelson said, and its numbers have been declining thanks to investigations, arrests and crackdowns by tech companies. She estimated that there are only about 20 active members in the country.

“That being said, we are seeing a number of other organizations, modeled after Atomwaffen, which have cropped up,” she said. Likewise, she said support has only spread for Atomwaffen’s “accelerationist” approach to white supremacism.

The man described by law enforcement as the leader of Atomwaffen’s Virginia cell, Andrew Thomasberg, is being sentenced in Alexandria on gun charges Friday.