Italy is a member of NATO (and Spain, too). If Israeli forces attack an Italian ship in international waters, it would constitute a declaration of war against every member state, and they will all be obliged to retaliate militarily. I am not sure everyone appreciates the gravity of what's happening around the flotilla, but this is shaping up to be a major international incident
Italy to deploy second naval ship in support of the Global Sumud Flotilla.
This is more about ensuring freedom of navigation in international waters and upholding maritime law.
Still, this is totally unprecedented and the tide is turning.