There is well-known for a long time official bullshit about "men who recently leaved military service and become mercenaries that have absolutely nothing to do with military".

Tons of such US and EU "mercenaries" in Ukraine, dead and still alive. Documented. It will be very reasonable to suppose that Israel is no any different. Especially taking in account that it's not something rare when US citizen is also a citizen of Israel and somehow Israel accounted among average American sheeple (including military) as much closer "ally" of USA than Ukraine.

So, if somebody claim that US military serve for Israel, that is just another confirmation of obvious thing, not some new claim with new information.