As many of you know, recently Netanyahu was issued an arrest warrant by the ICC, and many countries (ie Ireland, Italy, Spain, Netherlands etc) have stated that if he enters their country, he's getting arrested.

I know Putin also has one out for him too, but my question is, what would realistically happen if Netanyahu or Putin (or any other sitting heads of state) were arrested for this?

I know one of the obvious ones is a deputy leader would take control, but excluding that, what would realistically happen from a geopolitical viewpoint? Are there measures in place to try and prevent escalation by the detainee's country that may issue threats or something similar?

The odds of either of them getting arrested are low, but its something I was thinking about while reading some news.