[km3r]

That is an elementary understanding international law.

If after Oct 7th Israel went and killed a single child in retaliation, that would be unjust. Justification and proportionality are not measured like that.

Justification is established by a valid objective to go to war. Proportionality is measured in comparison to the military objectives. The Oct 7th attack clearly justifies the removal of Hamas. The proportionality of doing so is dependent on the size of Hamas's army (20k-30k), the size of their infrastructure (500 kms of tunnels), and their ability to separate their operations and operators from civilians.