Twelve U.S. National Guard members have been removed from securing President-elect Joe Biden's inauguration after vetting by the Federal Bureau of Investigation (FBI), including two who made extremist statements in posts or texts about the Wednesday event, Pentagon officials said. There were no specific threats to Biden.

All 12 were found to have ties with right-wing militia groups or posted extremist views online. The officials, a senior intelligence official and an army official briefed on the matter, did not say which fringe groups the Guard members belonged to or what unit they served in. The officials were not authorized to speak publicly and spoke to AP on the condition of anonymity. The officials told the AP they had all been removed because of "security liabilities."

Gen. Daniel Hokanson, chief of the National Guard, confirmed that Guard members had been removed and sent home but he said only two were for inappropriate comments or texts related to the inauguration. The other 10 were for other potential issues that may involve previous criminal activity or activities, but not directly related to the inaugural event.

Their removal from the massive security presence at the nation's capital comes as U.S. defense officials have been worried about a potential insider attack or other threat from service members following the deadly riot at the U.S. Capitol on January 6 by Trump supporters. The FBI has been working to vet all 25,000 National Guard in town. Officials have said that the Pentagon has found no intelligence so far that would indicate an insider threat.

But the FBI has also warned law enforcement officials about the possibility that right-wing fringe groups could pose as members of the National Guard, according to two law enforcement officials familiar with the matter.

"Much of the information," Hoffman said, "is unrelated to the events taking place at the Capitol or to the concerns that many people have noted on extremism. These are vetting efforts that identify any questionable behavior in the past or any potential link to questionable behavior, not just related to extremism."

Heigntened security in D.C.

Washington has been on edge since the deadly insurrection at the Capitol, which has prompted extraordinary security measures ahead of Biden's inauguration. A fire in a homeless camp roughly a mile (about 1.6 kilometers) from the Capitol complex prompted a lockdown Monday during a rehearsal for the inauguration.

Officials announced the closure of multiple bridges that connect Washington with Virginia, limiting the access routes between the capital city and populated suburbs to its limit. The closures further restrict travel in the greater D.C. area. 

U.S. Secret Service tightened security in and around the Capitol days earlier than usual in preparation, and the city center is essentially on lockdown with streets blocked, high fencing installed and tens of thousands of troops and law enforcement officers stationed around the area.

The FBI also warned of plans for armed protests at all 50 state capitals and in Washington. 

The Secret Service issued a bulletin over the weekend about what it sees as an "uptick" in National Guard troops, that reads: "No service members should be posting locations, pictures or descriptions online regarding current operations or the sensitive sites they are protecting" and urged them to stop immediately.

Asked about the bulletin, a spokesperson for the Secret Service issued a statement saying it "does not comment on matters of protective intelligence."

(With input from AP)