As the USA minister of defence, he is in all likelihood responsible for crimes against humanity/war crimes, for instance, the killing of people on small boats in the Caribbean, and the hundreds of school girls in Iran, to name just two cases. But who could sue him; it seems it is usually countries that do this, but could eg an organization of international lawyers do this? What would it take for an individual to get him sued? (Asking for a friend).


Not a lawyer, but the President being “authorized” to act doesn’t sound like they must. The next Democratic president could simply look the other way.
Besides, we’re in the era of Presidents being allowed to just ignore any inconvenient laws. Not that I think any plausible near-term Democrat president has the will to actually do this, but I’m willing to be surprised.
Whether or not a president is compelled to enforce it doesn’t change my stance.
The rule of law is a construct. People who control the use of force or access to resources can do whatever they want, whenever they want.
That said, the reason that it is significant to me that this law exists is two fold:
Putting things in law and leaving it there is a public statement about the priorities and values of a government.
I find it shocking that people hold out hope that some foreign body is going to stop or punish the US government for their atrocities when the USA has made it clear, from the beginning, that they oppose the ICC.
Trump’s vocal opposition is not new. Obama invoked the law in 2014. Part of the law is that the US will not participate in activities that put their soldiers at risk, which requires countries to agree to not prosecute or surrender US troops if they want the support of the US military.
Further to that, obama’s government launched a review of the law and decided to keep it.
Biden removed some of the trump sanctions from his first term.
The removal was because they thought there were more effective ways to object: