"War crimes can only be committed during times of armed conflict, either international or non-international, as understood under international humanitarian law. While it is necessary that the crime in question was committed during an armed conflict, this is in itself not sufficient: the crime must be sufficiently linked to the armed conflict. This so-called nexus requirement is satisfied if the armed conflict played a substantial role in the perpetrator’s decision to commit the crime, his or her ability to commit it, or the manner in which the crime was committed.

In order to define an act as a war crime, this act must, besides having nexus to an armed conflict, be a serious violation of international humanitarian law and entail individual criminal responsibility."

https://www.rulac.org/legal-framework/international-criminal...