Allusion to a line in Trump's speech, early in his presidency, at the CIA - he referenced a '5th column' and that it is/going to be removed.
In a 2017 speech to the CIA, President Trump mentionedâ€¦â€¦COLUMNS
"I will tell you, final time, although I will say it, when you let in your thousands of other people that have been trying to come in, because I am coming back â€“ weâ€™re going to have to get you a larger room. (Applause.) We may have to get you a larger room. You know? And maybe, maybe, it will be built by somebody that knows how to build, and we wonâ€™t have COLUMNS. (Laughter.) You understand that? (Applause.) We get rid of the COLUMNS."