Related Rule
Ukraine
Practice Relating to Rule 20. Advance Warning
Ukraine’s IHL Manual (2004) states:
If the combat situation permits, an effective announcement of the offensive actions that may affect the civilian population shall be made in advance (e.g. preventive firing of light weapons to induce the civilians to go to shelters). 
Ukraine, Manual on the Application of IHL Rules, Ministry of Defence, 11 September 2004, § 2.3.3.2; see also § 2.3.2.1.