I suspect it was not a U turn, they simply turned off the transponders since they are now out of Irish air space. As other anon stated, they only turn on ADS-B when they want to (to comply with civil aviation requirements in foreign countries for example) . What is weird about 5 C17's is that you must be moving a LOT of stuff or a LOT of troops to justify use of five of them. No link to AF1 path necessary for that to be weird.
You do not speak for me Anon. I suspect you do speak for someone with a vested interest in geopolitical outcomes. How is Mr Soros paying these days? I understand many of his puppets have not been receiving their checks recently.