Ahead of the rally planned for Saturday in support of those arrested in the Jan. 6 riot at the Capitol, police said they have gleaned intelligence on possible violence but are hopeful the day will unfold peacefully.

Authorities declined to disclose specific threats or speculate about their credibility but said that police will take a cautious approach to this weekend’s rally after authorities were caught flat-footed when supporters of President Donald Trump breached the Capitol nine months ago.

“What we do know is the chatter we heard before January 6, the threats turned out to be credible,” U.S. Capitol Police Chief J. Thomas Manger said at a news conference Friday. “So we’re not taking any chances.”

Capitol Police called on the National Guard to be on standby and requested support from neighboring police departments, including in Arlington County in Virginia and Montgomery County in Maryland. Authorities also reinstalled temporary perimeter fencing around the Capitol and encouraged lawmakers to avoid the building on Saturday. D.C. police activated all of its force for Sept. 17-18.

The “Justice for J6” rally is planned to begin at noon at Union Square, a public park near the Capitol Reflecting Pool. Organizers are expecting around 700 attendees, according to a permit application submitted to the U.S. Capitol Police Board by Look Ahead America, a group that has planned protests in support of people arrested in the riot.

Manger said he is most concerned about the potential for clashes between rallygoers and counterdemonstrators, who are expected to organize nearby. But his force is ready to meet challenges that may arise, he said, in part because of organizational changes it made after Jan. 6 — which included expanding its internal intelligence operation.

As part of its new protocol, the department has given intelligence briefings to rank-and-file officers and conducted multiple trainings with its civil-disturbance units in advance of the demonstration, Capitol Police said Friday. It has also run through exercises with multiple state, local and federal agencies to “test and validate the plan for this weekend.”

Manger cast the Saturday rally as an opportunity to practice robust security posture for future demonstrations that pose threats to the nation’s capital.

“The American public and members of Congress have an expectation that we protect the Capitol, and I’m confident that with the plan we have in place, we’re going to be able to meet that expectation,” he said.

Residents of D.C.'s Capitol Hill neighborhood share how recurring threats of violence impact the community ahead of the rally planned for Sept. 18. (Alice Li, Hadley Green/The Washington Post)

Organizers of the rally claim that many of those who stormed the U.S. Capitol and brawled with police, broke windows and threatened to harm lawmakers, were actually nonviolent and participating in a political protest. Nearly 140 police officers were assaulted during the insurrection. The attack led to the deaths of five people, one of them a police officer.

Now, rally organizers contend, hundreds of people who have been charged with federal crimes during the January riot are “political prisoners,” an assertion that has exploded beyond the far right and been embraced among some mainstream conservatives.

Matt Braynard, a former Trump campaign operative and executive director of Look Ahead America, has blamed a few “bad actors” for violence on Jan. 6 and has repeatedly insisted that his rally will be peaceful.

There did not appear to be widespread mass coordination among right-wing extremists to attend, researchers say. Instead, many users in far-right chat rooms have discouraged attendance, convincing themselves that the planned event is a “trap,” set up by federal officials to arrest them.

D.C. officials noted that there are a number of public events planned in the city Saturday and said officers will have increased visibility across the city.

D.C. Police Chief Robert J. Contee III said that D.C. police will enforce “no gun zones” around demonstration areas. D.C. law bans anyone — including those with conceal-carry permits — from carrying a firearm within 1,000 feet of First-Amendment activity.

“As a reminder, the District’s gun laws will be enforced,” he said Friday. “In the event we observe individuals in possession of a firearm, we will take police action.”

Also on Saturday, about one mile from the rally site, a collective of local antifascists are hosting an event at Freedom Plaza as a celebratory rally with food and music to denounce the presence of “Jan. 6 insurrectionists, Nazis, and white supremacists” in Washington. Those organizers have not provided a crowd estimate but encouraged families to bring children.

In a classified memo obtained by The Washington Post, the Department of Homeland Security said it assessed that some individuals connected to or opposing the rally “may seek to engage in violence but lack indications of a specific or credible plot associated with the event.”

“Our mission tomorrow is our mission every day,” Manger said. “And that is to protect everyone’s rights to free speech and to allow them to lawfully demonstrate.”

Nick Miroff contributed to this report.