I think the stumbling block is Hamas want a guaranteed end to the war in return for for the hostages and the Israeli government doesn't. Once Hamas gives up the hostages it has nothing to bargain with so it's inevitable, I'm afraid, that they will continue to hold out. Hostage taking is vile but it has been effective in the past as Israel has agreed terms in exchange for the return of their citizens. Israel has a great many Palestinians in their prisons who are there without charge and/or trial. In 2023 this included 300 women and children. I think Hamas might consider that these could be classified as "hostages"?
A drop in the ocean in the great schemes of things....but replicated by how many more
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