The agreement calls for the bodies to be returned within 72 hours. This was not a realistic goal, and everyone knew it, but Trump's orders to the negotiations team, Qatar, Hamas and Netanyahu: sign the deal and pretend it's all good, so he can have his parade.
That's how Trump works. No substance and all theatrics.
Israel knew not all bodies will be returned within 72 hours, but the families were expecting more than 4 bodies.
Israeli and Egyptian teams are working around the clock, but here's a scenario: a 10 story building is leveled. In the tunnels underneath it, there's an Israeli body. If you bring in bulldozers to dig it up, you'll end up with bits and pieces of bone, mixed with tons of rubble.
It would have to be excavated from the top down, carefully, like you would an archeological site, to preserve the remains. That could take weeks, or months.
They all knew that, but good luck making that clear to Trump.
Bottom line, I don't blame the families, they're going to keep the pressure as they should.
