Règle correspondante
Practice Relating to Rule 107. Spies
Section A. Definition of spies
Ukraine’s IHL Manual (2004) states:
Spies are persons who, acting secretly or by deceit, gather (or attempt to gather) information in the territory controlled by a party to the armed conflict with the purpose of further transmission of information to the adverse party. 
Ukraine, Manual on the Application of IHL Rules, Ministry of Defence, 11 September 2004, §