Mark Steven Domingo, 26, who had combat experience in Afghanistan and recently converted to Islam, faces federal terror-related charges for plotting mass casualties via a home-made bomb at a white nationalist rally in Long Beach this past weekend, officials said.

"This was a case in which law enforcement was able to identify a man consumed with hate and bent on mass murder, and stop him before he could carry out his attack," US Attorney Nick Hanna told reporters.

"Nevertheless, the criminal case outlines a chilling terrorism plot that developed over the past two months and targeted innocent Americans that he expected to gather this past weekend," he added.

Domingo was arrested Friday after receiving what he thought was a live bomb packed with nails that was delivered by an undercover agent.

According to court documents, Domingo expressed support in online posts and conversations with an FBI source for violent jihad and aspired to become a martyr by seeking retribution for attacks against Muslims.

After considering various options -- including targeting Jews, churches, and police officers -- Domingo decided to detonate an IED at the Long Beach rally, which ended up not taking place, authorities said.

 'The taste of terror' 

"At times Mr Domingo said that he wanted to kill Jews as they walked to synagogue," Hanna said. "At other times he said he wanted to kill and target police officers, attack a military facility or attack crowds at the Santa Monica pier."

He added that Domingo, of Reseda, a neighborhood in the San Fernando Valley in Los Angeles, even considered killing a neighbor as a prelude to a much larger attack.

Domingo, who served in Afghanistan between September 2012 and January 2013, apparently began mulling a terror attack in early March and decided to move forward after the March 13 mass shootings at two mosques in Christchurch, New Zealand, that left 50 people dead.

One message he posted to a private group online in early March referred to another mass shooting in Las Vegas in 2017 that left 58 dead.

"America needs another Vegas event... that would give them the taste of terror they gladly spread all over the world," he said.

In another posting on March 14, a day after the New Zealand attacks, he wrote: "There were mosque shootings in New Zealand. There must be retribution."

Hanna said Domingo repeatedly spoke about becoming a martyr and vowed to pledge allegiance to the Islamic State terror group if it managed to set up a presence in the United States.

 Rise in hate 

After several weeks of plotting with an undercover FBI informant, Domingo finally set his sights on the rally in Long Beach and bought several hundred three-inch (7.6-centimeter) nails to be used as shrapnel inside a pressure cooker bomb.

He believed the nails would be effective "because they would be long enough to penetrate the human body and puncture internal organs," the complaint says.

He was arrested after an undercover officer handed him an inert device he thought was active and the pair traveled to the Long Beach park where the rally was set to take place to conduct surveillance.

"I'm extremely glad to be announcing that we interdicted a potential terrorist attack, rather than outlining the FBI's response to yet another tragedy," said Paul Delacourt, assistant director in charge of the FBI's Los Angeles Field Office. 

"At no time was the public in danger and there is currently no known threat to public safety."

Domingo has been charged with providing and attempting to provide material support to terrorists. He faces up to 15 years in prison on the charge.

He was due to make an initial appearance on court later Monday.

His arrest comes two days after a 19-year-old California man, John Earnest, was arrested for shooting dead one worshipper and wounding three others at a synagogue near San Diego.

Last year, the Anti-Defamation League, which combats anti-Semitism and discrimination, reported a 57 percent leap in the number of anti-Semitic incidents in 2017, the sharpest yearly spike since the 1970s.