Practice Relating to Rule 64. Conclusion of an Agreement to Suspend Combat with the Intention of Attacking by Surprise the Adversary Relying on It
New Zealand’s Military Manual (1992) provides:
Any agreement made by belligerent commanders must be scrupulously adhered to and a breach of its conditions would involve international responsibility and liability for compensation, if ordered by a government, or personal liability which might amount to a war crime, if committed by an individual on his own authority.
The manual also states:
In general, it is contrary to modern practice to attempt to obtain advantage of the enemy by deliberate lying, for instance, by declaring that an armistice has been agreed upon when in fact that is not the case.
In addition, the manual states:
Violation of the terms of an armistice by an individual acting on his own initiative entitles the injured party to demand the punishment of the offender. If the party injured captures the offender, it may try him for a war crime.