I'm not 100% sure he would use it for short trips in the US, but for international trips he absolutely does. In fact here is a video of the current SECDEF boarding his E4B in Israel last year. Video.
I've looked over the directives that authorize travel to VIPs, and the actual executive travel regs and I can't find anything other than only tier-1 people can schedule executive aircraft (like service secretaries or chiefs of staff). My suspicion is that particular plane and the directives as to where/when it is used are probably classified. The only quasi-official stuff I saw was it is used in International travel of SECDEF. That makes complete sense because he has to have those capabilities wherever he is.
I did find a news article that had this blurb:
Periodic upgrades and 30-day stretches of heavy maintenance take jets out of an already limited rotation, so Secretary Austin currently only uses the E-4B for overseas trips.
I'm not 100% sure he would use it for short trips in the US, but for international trips he absolutely does. In fact here is a video of the current SECDEF boarding his E4B in Israel last year. Video.
Here is another one of Austin landing in Brussels.
I've looked over the directives that authorize travel to VIPs, and the actual executive travel regs and I can't find anything other than only tier-1 people can schedule executive aircraft (like service secretaries or chiefs of staff). My suspicion is that particular plane and the directives as to where/when it is used are probably classified. The only quasi-official stuff I saw was it is used in International travel of SECDEF. That makes complete sense because he has to have those capabilities wherever he is.
I did find a news article that had this blurb: