Secretary of State Marco Rubio and top White House adviser Stephen Miller on Thursday sought to paint a dark picture of the threat of “far-left terror” to the United States as they urged diplomats from around the world to “defend” their civilizations against the “scourge.”

In remarks focused almost entirely on the US, Miller spoke of the need to fight the “fatal cancer of civilization,” claiming that so-called left-wing terrorism, when “left to run its course, it always becomes a gulag.” He argued that the US’ political, legal, and judicial systems don’t work “if the threat of violence and terror goes on unchecked.” And he denounced Antifa protesters as “deformed,” saying, “their outer appearance becomes a manifestation of their inner hatred.”

“The greatest risk that we have is that our institutions have grown too soft and too cowardly to be able to defend themselves against a mortal threat,” Miller told a room full of representatives from more 60 countries and fellow Trump administration officials at the State Department on Thursday. “If your civilization is your home, you must defend it with the same passion and force as if an enemy intruder is inside your own house where your family lives.”