People have been rationalizing Hamas's attacking civilians in a whole bunch of ways, but like...
The second Intifada used a lot of "terror" tactics. Stuff like attacking civilians, suicide bombings in public places, that kind of thing. Before that, the PFLP engaged in attacks against civilians.
Hamas probably did kill those people deliberately, and they probably did it because they've seen it work. The second Intifada yielded the camp David talks.
I think we should get crystal clear on this: targeting civilians is an intentional tactical choice of both Hamas and the PLO.
You're right, I am