Premise: ed note–Trump is holding back the last 'payment' on this gift so that if/when Israel balks at coming to the peace negotiations table, he can withdraw the gift, leaving blame for it squarely with the Joosh State and making it plain that it is the intransigence on the part of Netanyahu & co that caused it, squarely affixing Netanyahu in the anger-crosshairs of his own people.
Hypothesis: Payment is something that can be held back.