US Rules of Land Warfare (FM 27-10), 1940, Article 358: "Subjects of reprisals.-The offending forces or populations generally may lawfully be subjected to appropriate reprisals. Hostages taken and held for the declared purpose of insuring against unlawful acts by the enemy forces or people may be punished or put to death if the unlawful acts are nevertheless committed."
no subject
"Subjects of reprisals.-The offending forces or populations
generally may lawfully be subjected to appropriate reprisals.
Hostages taken and held for the declared purpose of insuring
against unlawful acts by the enemy forces or people may be
punished or put to death if the unlawful acts are nevertheless
committed."