Federal authorities are watching political activists organizing protests ahead of next week’s Republican National Convention, warning that “anarchist extremists” pose a threat to Cleveland.

A “threat assessment” issued jointly by the FBI, Secret Service, and Department of Homeland Security warns law enforcement to be on the lookout for “potential indicators” of “violent anarchist extremist activity.” The indicators include “pilfering construction sites” for rocks, pipes, or bricks and “movement of newspaper containers and trashcans to create barricades” — but also carrying spray paint, eye drops, or wearing “clothing bearing anarchist symbols.”

The document, obtained by The Intercept, is dated July 7 and marked “For Official Use Only.” It says that the agencies had “no information to indicate a specific, credible threat to or associated with” the convention but also warns of the potential for a “lone wolf” terrorist attack or violence from Donald Trump supporters or people coming to protest him.

The only specific group identified in the document is described as “a known anarchist extremist network known as the Resist the Cleveland RNC,” which “is assisting anarchists by providing logistical support, training, and a communications platform for anarchist activities including anarchist extremist violence.” It notes that “known anarchist extremists” from Cleveland and elsewhere “have discussed the 2016 RNC and made plans to travel to Cleveland.”

The only evidence of the “network” provided is a link to a public Facebook page that describes itself as “dedicated to spreading information about the resistance to the 2016 RNC.” People have posted articles and basic information about the convention, links to the National Lawyer’s Guild and local medics, and events like “Stand Together Against Trump March and Rally,” “Art Making,” and “Circle the City with Love.” A second page cited in the report is titled “resistRNC Cleveland 2016 Transport Squad” and mainly consists of links to news articles about the convention and occasional requests to coordinate housing or rides.

A recent post on the page says, “This is not a organization. At all. This is just a page to share information.”

Lyz Bly, a Cleveland resident and one of the administrators of the first of the two Facebook pages, told The Intercept that the page was started in 2014, not long after it was first announced that Cleveland would host the convention. She helped convene a meeting at the local bookstore she co-founded to discuss the community’s response.

“We wanted to talk about how we could be a resource to activists who might show up from around the country, and we did have an early meeting that probably did have some anarchists at it,” Bly said. “It wasn’t anarchist plotting; it was, how can we organize, how can we help folks. All types of local groups and activists were there.” She said the page is loosely monitored by a group of people now, without any particular affiliation.

The Department of Homeland Security referred a request for comment to the FBI, which did not respond.

“If you’re posting something on Facebook publicly, everyone can access it, including the government,” said Gary Daniels, a spokesperson for the American Civil Liberties Union of Ohio. “People would have to be awfully naïve to think that these things aren’t being monitored for people coming to Cleveland for the RNC.”

The list of potential violent anarchist behaviors in the document seems to be drawn from reports of a May Day protest in Seattle last year, where 16 people were arrested after clashing with cops, along with the account of a single “officer of another law enforcement agency.”

Of course, there have been protesters of various stripes at every convention in recent memory; indeed, during the 2012 conventions, a similar intelligence briefing about anarchists was made public. But given the current heightened tension after a week of demonstrations around the country over police killings and the attack on officers in Dallas — combined with Trump’s incendiary rhetoric — both authorities and protesters are especially on edge.

The city of Cleveland has spent a reported $20 million in federal funds on riot gear, barricades, batons and more, and local activists have been visited and questioned by local and federal authorities. Cleveland has marked off a nearly 2-mile zone around the convention center, with designated protest areas. Inside the zone, people will be prohibited from carrying a variety of everyday items such as bike locks, tape, rope, sleeping bags, tennis balls, and water guns. With Ohio’s open-carry laws, however, real guns will be allowed.

Bly had an FBI agent and a local police officer at her door on the morning after the Fourth of July. They told her she was a “person of interest” and asked her about her plans for the convention and whether she was concerned about any lone-wolf types.

“They did this to a lot of people,” Bly said. “It was a ‘see something, say something’ kind of thing.”

“I’ve been an activist for a long time, but I’m a mother and a teacher and a scholar,” she said she told them. “I’m going to protest, but I’m going to try not to get arrested.”