The message, dated Thursday, was prepared by the agency for Chad F. Wolf, the acting secretary of Homeland Security, as he arrived in Portland to view the scene in person, according to a copy of the memo obtained by The New York Times. It listed federal buildings in the city and issues officers faced in protecting them.

The memo, seemingly anticipating future encounters with protesters in other cities as the department follows President Trump’s guidance to crack down on unrest, warns: “Moving forward, if this type of response is going to be the norm, specialized training and standardized equipment should be deployed to responding agencies.”

The tactical agents deployed by Homeland Security include officials from a group known as BORTAC, the Border Patrol’s equivalent of a S.W.A.T. team, a highly trained group that normally is tasked with investigating drug smuggling organizations, as opposed to protesters in cities.