We can’t. At least while the USA is a thing.

Even if the US wasn't a thing, punishing Zionists wouldn't be possible without subduing Israel through a literal war. Something which is not often attempted.

At best, we'd have the half-ass 'punishment' levied on states like Taliban-ruled Afghanistan, Djibouti, and North Korea, wherein the primary punishment is "It's slightly harder and more expensive for the elite to get their precious foreign luxuries."

Don't get me wrong, that's better than nothing. It's just...

Prevention is generally a more fruitful avenue than punishment, when it comes to international polities and ideologies even with just regional majorities.

The chance of seeing genocidal cunts swing, or even acknowledge their wrongdoing, are generally small. Even the worst genocide of modernity, the Holocaust, had only a relatively small number of Nazis punished, despite literally every major extant power agreeing on how horrific their behavior was, and quite literally destroying all military capacity for the Nazis to resist and occupying every inch of their territory.

At most, you might get a handful of them in international courts by internal politiking, like Slobodan Milošević, but even then we're unlikely to see the fully 'cathartic' end we want. "My dad is a war criminal" will still be sung proudly.