That is what proportionality means. Blowing up an orphanage to get one gunman bad.
Killing an army head quarters at the cost of one orphanage possibly acceptable.
That's really not how it works.
For starters there aren't fixed quotas of dead kids a military planner can refer to
And it would be more than tasteless to set up some kind of table which is allowable.
X number of kids depending on rank of the target.
Proportionality like a lot of international agreements on armed conflict isn't fixed in stone.
Some might think killing a load of kids to destroy one army HQ isn't proportionate.
Israel isn't a rogue state and has army lawyers to advise it on bombing.
So far , except for the pagers, it's always attempted to justify it's killing of civilians.
In Lebanon the argument is that it's told people to move out the way
In Gaza says the same. Plus it argues like you are that high status Hamas target justifies heavy civilian collateral damage.
What I'm saying is that post WW2 there has been developed body of international law / agreements to regulate armed conflict.
In a hypothetical case of killing a load of kids to destroy high importance target a case might be brought that this was not proportionate which can be defended.
This of course takes time. And it's where proportionality is defined and re defined.
The case I have posted about as example is targeted assassinations/ extra judicial killing
Where Israel succeeded in changing customary international law so that this is accepted as part of armed conflict where policing and war overlap
TBF there are posters here who are into military stuff. Thought this would be obvious.
One of the articles I posted was by ex military person.
And IDF / Israel put what Noura Erakat in her book on Israel/ Palestine a lot of Legal Work into justifying their actions.