Both the Korean War and Vietnam war killed millions,with significant civilian casualities. North Vietnam was carpet bombed,and both Napalm and chemical defoliants were used. The French,the US and the Chinese all did it and yet got away with it.
The US supplied Stinger MANPADs to UNITA during the Angolan civil war with Europe allowing such shipments. That war killed 500000 people and only ended when UNITA was defeated when its leader was killed. We helped prop them up.
FFS,look at the last 30 to 40 years of problems in Iran and Iraq- we helped foster that. The Shah of Iran,Saddam,etc.
We end up judging so many other poorer and weaker countries for war crimes,yet quietly absolve ourselves of any of the same justice for our own actions.
We have been involved in so many wars both directly and indirectly and helped so many dodgy people out there and do I wonder in 100 years time how we will be judged??