Fifth column, clandestine group or faction of subversive agents who attempt to undermine a nation’s solidarity by any means at their disposal. The term is conventionally credited to Emilio Mola Vidal, a Nationalist general during the Spanish Civil War (1936–39). As four of his army columns moved on Madrid, the general referred to his militant supporters within the capital as his “fifth column,” intent on undermining the loyalist government from within.
https://www.britannica.com/topic/fifth-column
Trump talking about the "5th column" while at the Sea Eye Eyh at the start of his administration.
Subversion has been underway since the night of the election win in 2016.