Related Rule
Practice Relating to Rule 1. The Principle of Distinction between Civilians and Combatants
Section C. Attacks against civilians
The Hellenic Navy’s International Law Manual (1995) states in its chapter on submarine warfare:
The aforementioned practice followed during the two World Wars by no means should be considered as sanctioning the exception of naval warfare from the rules of armed conflict. On the contrary, the fundamental principles of IHL treaties concerning the protection and respect of … civilians must be considered applicable. 
Greece, International Law Manual, Hellenic Navy General Staff, Directorate A2, Division IV, 1995, Chapter 7, Part III, § 4.
In 2006, during a debate in the UN Security Council on protection of civilians in armed conflict, the permanent representative of Greece stated: “Deliberate violent attacks against civilians … can not be tolerated and should come to a halt.” 
Greece, Statement by the permanent representative, Security Council meeting on protection of civilians in armed conflict, 5 December 2006.