> The ICC largely deals with things that are preemptory norms which apply regardless of if you sign the treaty.

That's irrelevant. Anyone can form an independent organization and proclaim that nations of the world are subject to the rules set forth by that independent organization.

The point is that they have no intrinsic authority.

Authority comes from either moral sanction (of the people, by the people / consent of the governed) or through force.

In other words, the enforcement mechanism has to come from those that opt-in to that organization. i.e: through mutual agreement.

Which means that any "violator" nation can then say "GTFO and I dare you to come at me and see the full force of my police (if you try to arrest my citizens) or my military (if the participating nations declare war on me in an attempt to enforce these 'laws')."

So it still can only come about through mutual agreements between nations. Otherwise it is nothing more than a rogue body that sends armed thugs to try and enforce its rules while nations get to say "We neither recognize nor agree to those rules, nor do we recognize your authority to enforce them. However, you are subject to our laws while you are trying to execute your 'warrants' on our soil. And we will arrest YOU and throw you in our jails if you interfere with the rights of any one of our citizens."

> In other words, the enforcement mechanism has to come from those that opt-in to that organization. i.e: through mutual agreement.

Tell that to the germans who were hanged at the nuremburg trials. They certainly didn't consent.

You are right to a certain extent, that enforcement requires agreement or force, but at the same time the general rules and procedures of international law do have some force to them. They have this force because they are widely agreed on. This includes Israel which broadly agree all these things are illegal, they just take issue with that specific court. However their donestic courts recognize all the things the icc prosecutes as crimes locally broadly speaking. (Well there is some dispute over what forced population transfer means, but that isn't one of the crimes in question for this warrant)