"Norman Finkelstein on Gaza conflict, Hamas goals and Iron Dome myth". He makes quite a few good points, including blaming Obama for allowing this to happen.
It's not the only atrocity but it was deliberately timed to coincide with the others that are ongoing and it was supported by the UK and US governments, as well as Egypt and others. So it is one for which we have some responsibility, since it is our governments that have allowed it to happen. The others, one could well say "Let them sort it out among themselves - there's enough of them". But when your own government takes a hand in arming those responsible for massacres, expropriations and genocide, then it's time to get up and do something, it's passed time in fact, and in the UK to change the government next year.
Not that the Opposition has any better record but at least they might be better on this than the present shower. And even if they are no better, we must always punish those in power for their depredations whenever we can, even if only by replacing them for the time being with another coterie of nincompoops.