So you don't think Egypt's actions amounted to an Act of War? Well Israel did.
Legally, Egypt’s action- closing the Tiran Strait for shipping- did not constitute an act of war in the legally recognised sense. Israel was repeatedly warned by the US government that its grievance with Egypt over the use of the straits would need to be resolved through diplomacy, not military force. The actions of mobilising your own troops within your own borders into defensive positions is also not an act of war.
Viewing these combined actions as a direct casus belli (an act of war)
Casus belli is not an act of war. It is a Latin phrase meaning 'occasion for war' — the act or event that a state cites publicly to justify going to war. It is the justification, distinct from the underlying causes. A state may go to war because it wants resources, fears a power shift, or sees a strategic opening, but it will frame the public reason as something narrower and more defensible: a border incident, a treaty violation, treatment of its nationals abroad.
The distinction between justification and cause matters because international law since 1945 cares about the justification.
Under the UN Charter, only two casus belli are lawful: self-defense under Article 51 (responding to an armed attack) and authorization by the UN Security under Chapter VII.
Everything else — honour, treaty breach, sovereignty disputes, treatment of nationals — has been demoted to political rhetoric without legal standing.
Israel launched a pre-emptive Six-Day War strike on Egyptian airfields on June 5, 1967
This surprise attack started the 1967 War. Your rhetoric that Egypt started it has no legal standing and is not reflected in the historical record of the 1967 war.