This recent video by RealLifeLore drives it home: https://www.youtube.com/watch?v=550EdfxN868&t=1504s
the last time in history that Sovereign American territory was invaded and occupied by a
hostile foreign power was between 1942 and 1943 when the Japanese occupied the
small and sparsely populated Alaskan islands of ATU and Kisa which they struggled to reinforce with supplies and
were only able to hold on to for a year before getting overrun by much better supplied American and Canadian soldiers
Up until 9/11, the US people had forgotten what it was like to be on defense.Later in the video: https://youtu.be/550EdfxN868?si=gpTplY4Z36tJPxLv&t=2706
that doesn't mean that the US cannot be hurt or have its interests disrupted in other ways the US Mainland
can obviously still become the subject of major attacks from hostile foreign powers if not outright invasions and the
biggest and worst attack that ever befell the US on its own territory happened recently only 23 years ago