Far-right groups such as the Proud Boys and The Oathkeepers whose members were involved in the riot of the U.S. Capitol last week are advising followers to stay away from major cities where there will be a large law-enforcement presence next week, either by lying low entirely or gathering away from state capitols.

Nonetheless, extremism watchdog groups and former law-enforcement officials say there is still a threat from lone-wolf extremists who are inspired by such groups. The far-right groups, which don’t accept the legitimacy of President-elect Joe Biden’s victory over President Trump, could become more aggressive in the coming months after security is lowered, the watchdogs and ex-officials said.

“They’re not going to go marching up to some building, carrying a flag and using a bullhorn,” a former FBI agent who has worked on domestic terrorism cases said of the most worrisome current threat. “These are people that honestly are intent on doing what it is they’re going to do under the cover of darkness. They’re going to do it in a way that people are not going to see them coming.”