Israel bombed the Gazan side of the crossing, destroying the roads and making it unpassable for trucks.
Then Egypt could have sent soldiers in. In fact, I bet Israel would have been totally fine if Egypt simply took over the entire Gaza area. The entire war could end tomorrow if Egypt simply agreed to do that.
Guess who would have to enforce it by just not sending weapons.
Nobody. Previous aid has nothing at all to do with implementing the UN ceasefire resolution. Biden already stopped sending any types of weapons that could be used in Gaza because Israel has a terrible PM. Israel can buy any weapons it wants on the international market. The idea that the US could magically stop the war is nonsense, as is the idea that Biden has done nothing, as is the idea that the countries in the region do not have the chief power and responsibility to do what they could.