The defendants were arrested for plotting to bomb government facilities and public places after federal authorities uncovered their plans to engage in "violent jihad," FBI spokeswoman Laura Eimiller said.
According to a federal complaint unsealed Monday during their initial appearances, Sohiel Omar Kabir, 34, introduced two other California men to the radical Islamist doctrine of Anwar al-Awlaki, a deceased al-Qaida leader.
The two, Ralph Deleon, 23, and Miguel Alejandro Santana Vidriales, 21, converted to Islam in 2010 and began engaging with Kabir and others online in discussions about jihad, including posting radical content to Facebook and expressing extremist views in comments.
In one online conversation, Santana told an FBI undercover agent that he wanted to commit jihad and expressed interest in a jihadist training camp in Jalalabad, Afghanistan.
The complaint also alleges the men went to a shooting range several times, including a Sept. 10, 2012, trip in which Deleon told a confidential FBI source that he wanted to be on the front lines overseas and use C-4, an explosive, in an attack. Santana agreed.
"I wanna do C-4s if I could put one of these trucks right here with my, with that. Just drive into, like, the baddest military base," Santana said, according to the complaint, adding that he wanted to use a large quantity of the explosive.
"If I'm gonna do that, I'm gonna take out a whole base. Might as well make it, like, big, ya know," Santana said.
At the shooting range that day, both Santana and Deleon said they were excited about the rewards from becoming a shaheed, Arabic for martyr, according to the complaint.
Authorities allege Kabir traveled to Afghanistan and communicated with Santana and Deleon so he could arrange for their travel to join him and meet with his contacts for terror organizations. They later recruited 21-year-old Arifeen David Gojali.
It wasn't immediately known if any of the men has an attorney. The FBI didn't immediately return a call seeking comment.
If convicted, the defendants each face a maximum penalty of 15 years in federal prison.