Or they use the excuse that terrorists are hiding under hospitals and schools, so dropping bombs on these things are perfectly acceptable. In my book that's morally indefensible and makes them not very different to Hamas butchers.
Or if you can accept that, maybe crashing planes into the WTC towers is acceptable too (and what about a military target like the Pentagon)...
You would say the same about any group that did the same things to you as the Israeli have done to Palestinians. Answer this: will these actions by Israel decrease or increase the number of people who think that way? Even if they kill all the Palestinians and get rid of the threat in Gaza, they'll just create more, deeper and stronger hate against themselves in the region and the world. If at any point in time they lose the support of the most powerful country on earth, they'll be in huge danger and they can only blame themselves for creating that danger.
Unfortunately, this is true of both sides, and one side seems much closer to accomplishing its goal than the other side.
> what would you have them do
The same question was answered here: https://news.ycombinator.com/item?id=44718080