Google “Nuke Aswan Dam”.
Of course the Israelis have gone over every conceivable scenario for breaching the Aswan High Dam. It is said the 1973 war ended in ceasefire only when Sadat was persuaded that an attack on the dam was imminent.
Most studies I have read say the Aswan Dam is vulnerable only to a nuke strike due to its sheer massiveness (it’s a huge pile of quarried rubble, not stressed concrete), but were it to be breached, the flooding from Lake Nasser would not wash Cairo into the sea.
The flooding would however destroy the Egyptian agrarian economy and they already have to import food.
Morsi will huff & puff & threaten, but even he knows what that got Nasser. And the chances of a 1973 style Yom Kippur sneak attack are practically nil.
However, there’s a huge overpopulation in Egypt of unemployed womanless young males. Losing a few million of them in hopeless jihad against the hated Jews wouldn’t be that great a loss to the Ikhwan leadership.