What do you think is adequate sanction then?
If Israel state had joined up with International criminal court ( the ICC) which in end it didn't it could have referred war crime allegations to it for investigation.
But it's not part of ICC.
Secondly they could have targeted leaders of Hamas ( which they have done before). Not saying I agree with that. But it's better than collective punishment.
What IDF / Israeli government are doing now in Gaza is the Dahiya military strategy taken to extreme.
Dahiya doctrine was developed to use against armed groups by destroying infrastructure etc so in end civilian population withdraw support from armed militants. First used in Lebanon by IDF
It specifically targets areas with overwhelming force. Destroying civilian infrastructure and economy so much that it would take years to rebuild. Idea being civilian would stop any support for armed militants.
en.m.wikipedia.org
The criticism of it is that it is tantamount to collective punishment of a civilian population.
Secondly as this Israeli online magazine reports in case of Gaza the guidelines for targeting armed militants like Hamas have been so reduced that those compiling targets are not all happy with this. Basically it used to be that targets of leaders of Hamas would only be agreed if civilian casualties could be minimised. This is no longer the case
As has been shown in Gaza
Report here
Permissive airstrikes on non-military targets and the use of an AI system have enabled the Israeli army to carry out its deadliest war on Gaza.
www.972mag.com
There needs to be a UN ceasefire.
With investigation of war crimes on both sides
Secondly as head of UN says dealing with the context. That is the ongoing lack of state for Palestinians/ illegal settlement building in West / settler violence over the years. Etc
Head of UN got a lot of stick for saying there is a context to this. That this didn't start on 7th October.