First site, wikipedia. Results
not promising. There are eight PEOPLE on this list, not necessarily even soldiers.
Quick after-note: I didn't even have to go past Wikipedia.
----
1) Robert Bales was sentenced to Life without Parole for a massacre in Afghanistan. This was under President Nixon. This is the ONLY instance I found of a soldier being tried and convicted for actual war crimes rather than being given, say, a discharge.
2) Roosevelt was President when Jacob A. Smith ordered US troops to kill every male in the immediate area over 10 in the Philippines. Was not tried for war crimes. Perjured himself in front of a court martial. Was made to retire peacefully. Never tried for War Crimes.
3) There are a
goddam slew of war crimes witnessed during WW2. These include rape (Okinawa being the most well-known, IMO), firing upon civilian vessels, the list goes on. Both Roosevelt and Truman were President in 1945, when the invasion of Okinawa began. Notable excerpts:
Samuel Saxton, a retired captain, explained that the American veterans and witnesses may have intentionally kept the rape [In Okinawa] a secret, largely out of shame: "It would be unfair for the public to get the impression that we were all a bunch of rapists after we worked so hard to serve our country."
In the Laconia massacre, U.S. aircraft attacked Germans rescuing survivors from the sinking British troopship in the Atlantic Ocean. Pilots of a United States Army Air Forces (USAAF) B-24 Liberator bomber, despite knowing the U-boat's location, intentions, and the presence of British seamen, killed dozens of Laconia's survivors with bombs and strafing attacks, forcing U-156 to cast its remaining survivors into the sea and crash dive to avoid being destroyed.
Secret wartime files made public only in 2006 reveal that American GIs committed 400 sexual offenses in Europe, including 126 rapes in England, between 1942 and 1945.
4) There are similar piles of reports for the Vietnam War.
My Lai seems the biggest incident, which involved women and children and numerous horrific acts. This would have been, primarily, Nixon's Presidency.
----
CONCLUSION AFTER SOME VERY CURSORY RESEARCH: I mean there are A LOT OF INSTANCES of very, very clear war crimes committed by specific, known individuals both under and not under orders from their superiors, across multiple party lines (I found data going as far back as the
Whigs) that were simply ignored in the USA. There's enough here
just on wikipedia that I could do this literally all day long. There's basically one or more for every major or minor conflict the US has ever been involved in. You'll find plenty of instances where they are convicted
in connection with war crimes or some such and given, eh a couple years or a dishonorable discharge.