Goodluck, a little correction, in international law, the closing of an international waterway (Suez canal, Sharam al Shekh) is a legitimate casus belli .1956 was preceded by closing the canal to Israeli ships (the fact that the then weak Israel cooperated with the imperialist French and Britons is probably the only fault). 1967, was preceded, once more by a blockade on sea lanes, as well as the removal of the UN buffer forces from the Sinai, also a casus belli. Yes, the actual opening of the massive warfare was a military preemptive strike in both cases, but the war was started by Egypt, in both cases creating bellicose facts in the field. If memory serves, in 1967, a ship was sent to try and break the blockade, and when it was fired on it withdrew, that was the act of war fully justifying the following actions. The only true "preemptive action" was bombing of the Iraqi nuclear facilities, but legally, Iraq never signed an armistice with Israel, so all this time there is still a state of active war between them, including the lobbing by Iraq of tens of scud missiles on Israel during the gulf conflict.
Zeev