Appearing in front of D.C. magistrate judge Zia Faruqui, Floyd Roseberry, 49, pleaded not guilty to both charges against him, including attempting to use a weapon of mass destruction.
A doctor deemed he was competent after examining Roseberry following a change to his medication regimen.
Roseberry will remain in pretrial detention ahead of his next scheduled appearance in court on Oct. 8.
Back in August, Roseberry pulled up in his truck with no license plate outside the Library of Congress, just eight months after the rioting at the U.S. Capitol.
During the standoff, Roseberry -- a self-proclaimed patriot -- took to Facebook Live inside his truck.
"I'm up here in Washington, D.C., there's a Capitol or something. There's another Capitol. The police are coming. I'm trying to get Joe Biden on the phone," Roseberry said.
All of this was said as Roseberry held a canister that he claimed was a bomb that could only be detonated if the windows were shattered. During his rant, Roseberry made anti-government threats as well as comments on the recent events in Afghanistan, health care and the military. At one point, the suspect called for President Biden to step down; in exchange, he would leave his truck.
"You step down out of office, I'll step down out of this truck," Roseberry said.
In a separate video two days earlier, Roseberry echoed far-right conspiracy theories about Democrats being arrested and former President Donald Trump being reinstated as president. He also called upon "the South" as well as talks to "revolution" all while targeting migrants from Mexico and Afghanistan.
"The revolution is on. It's here. It's today," Roseberry said. "Just come out and talk to me, Joe. America's tired of it. "I'm not the one setting this bomb off, Joe. You are. You're gonna be the one setting this off -- not me."
Facebook would go on to remove Roseberry's page as authorities began to investigate the videos. ABC News reported that Roseberry followed President Donald Trump's candidate page, Donald Trump Jr's page and a "White Lives Matter" page.
Roseberry's ex-wife, Crystal Roseberry, said she had seen images of the man in the standoff at the Capitol and confirmed to The Associated Press that it was her ex-husband. She said had never known him to have explosives, but that he was an avid collector of firearms.
Investigation in North Carolina
In North Carolina, local authorities searched a Cleveland County home along the 3000 block of Blacksburg Road connected to Roseberry after being alerted by FBI agents.
Randy Evans, a neighbor to Roseberry, told ABC-affiliate WSOC he had no idea what Roseberry was capable of and never expected him to make such headlines. He said another neighbor had filed a complaint after hearing loud bangs from Roseberry's property.
"We have no reason to believe that there is any danger to the community here in Cleveland County -- but that is our goal to eliminate any possible threats here," said special agent Bobby Wells with North Carolina's sector of the FBI.
Roseberry had no prior history with federal authorities; however, he had a "limited history" of arrests in Cleveland County, according to Sheriff Alan Norman.
In the meantime, the United States Capitol Police is working in conjunction with the FBI Washington Field Office to investigate Roseberry's background and the motive.
The Associated Press and ABC News contributed to this report.