WASHINGTON (NewsNation Now) — With troops in riot gear and barriers blocking access to the Capitol, Joe Biden was safely sworn in as president from behind miles of fencing.

The oath of office took place in a Washington on edge, two weeks after rioters attacked the U.S. Capitol.

Law enforcement officials contended not only with the potential for outside threats but also with rising concerns about an insider attack. Officials were monitoring members of far-right extremist and militia groups, increasingly concerned about the possibility such groups could stream into Washington and spark violent confrontations, a law enforcement official said.

There were a few scattered arrests, but no serious disruptions in the city during Biden’s inauguration ceremony.

As Biden put it in his address: “Just days after a riotous mob thought they could use violence to silence the will of the people, to stop the work of our democracy, to drive us from this sacred ground, it did not happen. It will never happen. Not today. Not tomorrow, not ever, not ever.”

After the deadly attack that killed five on Jan. 6, the U.S. Secret Service stepped up security for the inauguration early, essentially locking down the nation’s capital. More than 25,000 troops and police were called to duty. The National Mall was closed. Checkpoints were set up at intersections.

In the hours before the event, federal agents were monitoring “concerning online chatter,” which included an array of threats against elected officials and discussions about ways to infiltrate the inauguration, the official said.

And 12 National Guard members were removed from the security operation a day earlier after vetting by the FBI, including two who had made “inappropriate” comments or texts. Pentagon officials wouldn’t give details on the statements. The FBI vetted all 25,000 members in an extraordinary security effort in part over the presence of some ex-military in the riot.

Gen. Daniel Hokanson, chief of the National Guard Bureau, confirmed that Guard members had been removed and sent home. He said the other 10 cases were for potential issues that may involve previous criminal behavior or activities but were not directly related to the inaugural event.

Pentagon spokesperson Jonathan Hoffman said the vetting went beyond ties to extremist groups.

Hoffman said they cover any “questionable behavior in the past or any potential link to questionable behavior.”

“We’re not asking questions right now,” Hoffman said. “We’re not asking questions of people who are flagged. We’re out of an abundance of caution, taking action, and immediately removing them from the line of duty at the Capitol and the events taking place, and then we will address them whether it’s through law enforcement, if necessary, or through their own chain of command.”

In addition to the thousands of National Guard troops, hundreds of law enforcement officers from agencies around the country were also brought into Washington. The increased security is likely to remain in the nation’s capital for at least a few more days.

In a lighter moment Wednesday, a crew from NewsNation affiliate WGN-TV filmed a young boy delivering cookies to members of the National Guard; his way of saying thanks for protecting his city.

4-year-old Kavi Sadar’s parents say his neighborhood’s been a little scary since the riots– and the cookies were his idea. The guardsmen responded with a gift of their own: a U.S. flag patch that brought a huge smile to the little boy’s face. 

His family hopes security around the capital will be lifted soon. The Secret Service has given no indication when that will happen, but restrictions could begin to ease as soon as Thursday.

The Associated Press contributed to this report.