Can most military and VIP aircraft out of Andrews AFB transmit false ADS-B signals? Here is the ADS-B tracking of Navy P-3 Orion that seems to be violating Iranian air space tonight if the ADS-B is correct. An Iranian fighter was launched heading in it's direction but did not approach it. Two nights ago I was watching on globe.adsbexchange and flightaware the tracking of AF1 was transmitting. It was about 2 miles out from the air field for a landing and the ATC tower noted to ground crew VIP traffic is 10 miles out. It showed it landing when in fact it was still in the air. I know they are allowed to turn off their ADS-B anytime they need to for security reasons.
It is certainly possible, and also happens with some regularity. Here is an article discussing a recent USAF RC-135 flight over the South China Sea in which the RC-135 changed it's Mode S identifier to that of some Malaysian-registered plane.
At some point, the plane’s Mode-S number suddenly changed, from AE01CE to 750548. That’s the ICAO number for an unknown Malaysian aircraft. The RC-135W, call sign RAINY51, then flew a racetrack pattern between Hainan Island and the Paracel Islands, an archipelago in the South China Sea that China claims, but whose ownership is in dispute.
Relevant twitter thread linked in the article, with ADSB Exchange screenshots