A 727, especially one that is being sought, could not get close to the US without attracting all kinds of unwanted attention. An aircraft at that altitude (20,000+ feet) without a transponder, or one without a filed flight plan, or one that is not following proper flight procedures, or vectoring in from an unusual direction, or one that does not respond to communication.... You get the picture.
Exactly what someone might have in mind. Then it goes KABOOM when failure to respond to communication draws fire from a fighter jet.