Related Rule
Ukraine
Practice Relating to Rule 3. Definition of Combatants
Ukraine’s IHL Manual (2004) states:
1.2.22. Combatants (those who fight) are members of the armed forces of a Party to an armed conflict (other than medical personnel and chaplains). They have the right to participate directly in hostilities.
1.2.23. “Partisans” means persons who voluntarily fight as a part of organized partisan forces in a territory occupied by an adverse party (or is under the control of a reactionary regime), for the freedom and independence of their homeland.
Partisans are combatants if they are under a command responsible for their conduct, have insignia distinguishing them from the civilian population, carry their arms openly and respect the rules of international humanitarian law.
Fighters for national liberation movements are equal to the regular armed forces of a State, i.e. they are considered as combatants.
1.2.24. Non-combatants (those who do not fight) are members of the armed forces who provide assistance to them but take no direct part in hostilities. These are medical personnel, chaplains, war correspondents and so forth. …
Such persons become combatants in case of their direct participation in hostilities. 
Ukraine, Manual on the Application of IHL Rules, Ministry of Defence, 11 September 2004, §§ 1.2.22–1.2.24.