The South African government wants the leadership of Israel to be investigated for genocide.
This creates an obligation on South Africa to do something to prevent what some call the "crime of crimes".
Genocide is a crime under international law that was defined and codified during the early days of the UN in the 1940s and was in response to the Armenian genocide by the Ottomans during World War I and, later, the Nazi policies of the systemic murder of the Jewish people during World War II.