text: The Wounded and Sick
  4-19. Acts harmful to the enemy by a person of a military medical unit or facility, or a medical ground
  transport resulting in its loss of protected status do not necessarily warrant denial of respect and protection
  to that person’s unit or facility, or medical ground transport or to other military medical units or facilities, or
  medical ground transport.
  4-20. The obligation to refrain from the use of force against a medical unit acting in violation of its mission
  and protected status without due warning does not prohibit individuals or units from exercising their right of
  self-defense (see DOD Law of War Manual, 7.10.3.2).
  EXAMPLES OF ACTIONS OR CONDITIONS THAT DO NOT DEPRIVE MEDICAL UNITS AND
  FACILITIES OR MEDICAL GROUND TRANSPORTS OF PROTECTION
  4-21. The following are examples of actions or conditions that do not constitute “acts harmful to the enemy
  outside of their humanitarian functions” that would cause a medical unit or facility, hospital ship, or medical
  transport to lose its entitlement to protection (GWS arts. 21, 22, 35; see DOD Law of War Manual, 7.10.3.3):
  * Arming military medical personnel for protection against unlawful attacks. Military medical
  personnel and units may be armed for defense of themselves and the wounded and sick in their
  charge against unlawful attacks (GWS, art. 22).
  * Defensive devices of hospital ships and military medical aircraft. Equipping hospital ships and
  military medical aircraft with defensive devices—such as chaff for protection against over-the-
  horizon weapons or similar threats—is not prohibited, provided that such devices are not used to
  commit acts harmful to enemy military forces acting in conformity with the law of war.
  * Use of non-medical military personnel for security. The use of non-medical personnel, in the
  absence of armed orderlies, as a picket, sentries, or as an escort for security against unlawful
  attacks does not cause the medical units, facilities, or ground transports to forfeit their protection
  (GWS, art 22).
  * Temporary presence of small arms and ammunition recovered from the wounded and sick.
  The temporary presence of small arms and ammunition recovered from the wounded and sick,
  within the military medical unit, installation, hospital ship, or sick-bay before they are handed over
  to competent authorities does not cause the forfeiture of their protection..
  * Presence of military veterinarians and equipment. The presence of military veterinarians and
  their equipment within a medical unit or facility or transport to which they are not assigned does
  not cause the forfeiture of protection.
  * Temporary presence of combatants. The temporary presence of combatants within a military
  medical unit or facility (for example, to visit or leave wounded or to escort a prisoner to facilitate
  the prisoner’s care) does not automatically constitute an act harmful to the enemy that result in
  loss of protected status. As a feasible precaution, combatants should avoid unnecessary presence
  within a medical unit or facility.
  * Temporary presence of military objectives. The temporary presence of objects that are military
  objectives, such as a tactical vehicle or aircraft within a military medical unit or facility (for
  example, a military vehicle that is not protected as medical aircraft or transport used to deliver the
  wounded and sick to a medical facility) does not automatically constitute an act harmful to the
  enemy that forfeits its protection from being made the object of attack (see DOD Law of War
  Manual, 7.10.3.6). However, commanders of military medical units and facilities should establish
  procedures during international armed conflict to ensure that the non-medical transports do not
  remain unnecessarily within or near military medical units or facilities.
  * Care for civilian wounded or sick. Care for civilian wounded or sick does not cause medical
  units, facilities, or ground transports to forfeit their protection.
  * Transport of medical equipment and personnel. Equipment intended exclusively for medical
  purposes or military medical personnel over and above normal mission requirements, either
  stockpiled in military medical units and facilities or transported in medical ground transports, does
  not cause medical units, facilities, or ground transports to forfeit their protection.