Is a civilian protected by law of war if they may provide a vital information to their military and cannot be detained?
<p>The general rule is that civilians are protected persons in military conflicts.  But civilian casualties can be excused if associated with military necessity.</p>
<p>I can easily imagine a situation, in which a civilian is an accidental witness of a covert military operation.  They can not be detained, as that would require delegating a soldier (or more) to guard them, which may jeopardize the operation.  And leaving them free definitely jeopardizes the operation, as they may inform their military.</p>
<p>Does such a civilian witness constitutes a legitimate military target?</p>

<h2>Non-combatants are protected</h2>
<p>See <a href="https://law.stackexchange.com/a/67684/344">https://law.stackexchange.com/a/67684/344</a></p>
<blockquote>
<p>1 All persons who do not take a direct part or who have ceased to take part in hostilities, <strong>whether or not their liberty has been restricted</strong>, are entitled to respect for their person, honour and convictions and religious practices. <strong>They shall in all circumstances be treated humanely, without any adverse distinction. <em>It is prohibited to order that there shall be no survivors.</em></strong></p>
<p>2 Without prejudice to the generality of the foregoing, the following acts against the persons referred to in paragraph 1 are and shall remain prohibited at any time and in any place whatsoever:</p>
<ul>
<li>(a) violence to the life, health and physical or mental well-being of persons, <strong>in particular murder</strong> as well as cruel treatment such as torture, mutilation or any form of corporal punishment;</li>
</ul>
</blockquote>
<p>The civilian can be detained for as long as that is militarily necessarily and if that means someone must be delegated to guard them, tough. Or they can be released if it’s safe (for the civilian) to do so and if that jeopardizes the mission, tough.</p>
<p>No one said being a soldier was easy.</p>

military laws-of-war geneva-convention war