I think because for two reasons, first they do not want to see what happened to the Maylaisa Airlines plane which was shot down last work over eastern Ukraine happen to an American plane. Second because there is a sense that Israel is going to do something big in regards to riding Gaza of Hamas, once and for all.
“something big”
Please. Make My Day!
Israel can significantly reduce the presence of Hamas in Gaza in the short term, but in regards to "ridding Gaza of Hamas" it would likely require following the advice Arnaud Amalric gave to troops attacking the Cathar stronghold of Béziers during the Albigensian Crusade.