WASHINGTON — Twelve U.S. Army National Guard members have been removed from the presidential inauguration security mission after they were found to have ties with right-wing militia groups or posted extremist views online, according to two U.S. officials. There was no threat to President-elect Joe Biden, they said.

The officials, a senior intelligence official and an Army official briefed on the matter, did not say which fringe group the Guard members belonged to or what unit they served in. The officials were not authorized to speak publicly and spoke to The Associated Press on condition of anonymity.

Their removal from the massive security presence at the nation’s capital comes as the FBI worked to vet all of the 25,000 National Guard troops headed to the area for Biden’s inauguration Wednesday. 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 Jan. 6 by Trump supporters that shocked the nation.

Acting Defense Secretary Christopher Miller said in a statement Monday that vetting of National Guard troops continues and that the Pentagon has found no intelligence so far that would indicate an insider threat.

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 from the Capitol complex prompted a lockdown Monday during a rehearsal for the inauguration.

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.

Federal Law Enforcement Officials Concerned About Photos Taken of Checkpoints

Federal law enforcement officials have also been wary of increased surveillance of military and law enforcement checkpoints and other positions after National Guard troops reported people taking pictures and recording them, said the law enforcement officials, who spoke to the AP on condition of anonymity to discuss ongoing security matters.

The Secret Service issued a bulletin over the weekend about what it sees as an “uptick” in National Guard troops posting pictures and details of their operations online.

The Associated Press obtained the “all concerned” message sent to all National Guard troops coming to Washington. Without getting into specific postings, the bulletin read: “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.”

Contacted by the AP Tuesday morning, the National Guard Bureau referred questions to the U.S. Secret Service and said: “Due to operational security, we do not discuss the process nor the outcome of the vetting process for military members supporting the inauguration.”

Over the summer, a man was arrested in Los Angeles for impersonating a National Guard member during protests in the city near Los Angeles City Hall. The man, Gregory Wong, was carrying a sidearm and assault rifle but was taken into custody after actual Guardsmen confronted him when they noticed things out of place on his uniform.