In the definition of objects as military objectives (see Rule 1 (y)), the following criteria apply:
(a) The “nature” of an object symbolizes its fundamental character. Examples of military objectives by nature include military aircraft (including military UAV/UCAVs); military vehicles (other than medical transport); missiles and other weapons; military equipment; military fortifications, facilities and depots; warships; ministries of defence and armaments factories.
(b) Application of the “location” criterion can result in specific areas of land such as a mountain pass, a bridgehead or jungle trail becoming military objectives.
(c) The “purpose” of an object – although not military by nature − is concerned with the intended future use of an object.
(d) The “use” of an object relates to its present function, with the result that a civilian object can become a military objective due to its use by armed forces.
- Subject to the other requirements of the definition (see paragraph 3 of the Commentary on the chapeau to this Rule), there are four alternative criteria qualifying an object as a military objective: nature, location, purpose or use. These four criteria are the core of the definition of military objective, and they are analyzed in some detail in the four subparagraphs of this Rule.
- As a practical matter, attacks are most commonly based on an object’s nature (generally the enemy’s military equipment or installations) or by use by the enemy; qualification by purpose (the enemy’s intended future use of an object) or location is less common.
- The definition of military objective not only requires that an object “make[s] an effective contribution to military action” “by nature, location, purpose or use”, but also that its “total or partial destruction, capture, or neutralization, in the circumstances ruling at the time, offers a definite military advantage” (see Rule 1 (y)). As indicated in paragraph 3 of the commentary to Rule 1 (y), compliance with the first criterion will generally result in the advantage required of the second.
- In order to qualify as a military objective by nature, the object in question must have an inherent characteristic or attribute which contributes to military action. Military equipment and facilities most clearly qualify on this basis, as do tanks, military aircraft, military airfields, or military barracks. Even when not in use, such objects always constitute lawful targets during armed conflict.
- As mentioned in Rule 22 (a), military objectives by nature include Ministries of Defence. This will be the case even if such Ministries are staffed in part by civilians. Of course, to the extent that a Ministry of Defence has physically separate non-defence departments, as in the case of the Swiss Federal Ministry of Defence, Civil Protection and Sport, its facilities devoted exclusively to such civilian functions are not military objectives by nature.
- The examples mentioned in Rule 22 (a) are non-exhaustive. Their distinctive feature is that they qualify as military objectives by nature in all circumstances. Other objects could qualify as military objectives by nature as well (see Rule 23).
“Location” relates to selected areas that have special importance to military operations, such as a particular mountain pass that may offer enemy armed forces a route of retreat in the face of a planned attack. Because of the location of the pass, it is lawful to block it through air attack, irrespective of use. Similarly, an attacker may wish to blind the enemy by depriving it of high ground from which it could observe the attacker’s operation. It may also destroy natural cover in the area, to prohibit the enemy from using it as an observation point. In these cases, it is not actual “use” or the enemy’s intended future use (“purpose”) that matters. The governing criterion is the need to attack a location so as to enhance or safeguard the attacker’s operations or to diminish the enemy’s options.
- It is essential to distinguish “purpose” from “use” (see Rule 22 (d)). The latter refers to present function of an object, whereas the former focuses on intended future use. The purpose criterion recognizes that an attacker need not wait until an object is actually used for military ends before being allowed to attack it as a military objective.
- The key issue in determining purpose is the enemy’s intent. In many cases, the enemy’s intent as to the future use of an object is clear. An example of such clarity is when reliable intelligence or other information indicates that an apartment building is being renovated with a view to serving as a military barracks. The apartment building becomes a military objective by purpose, regardless of its actual or ultimate use.
- Often, however, the enemy’s intent is not clear. In such circumstances, it is necessary to avoid sheer speculation and to rely on hard evidence, based perhaps on intelligence gathering. The dilemma is that intelligence is of varying degrees of reliability. The attacker must always act reasonably, i.e. as would be proper under a similar set of circumstances for any other Belligerent Party. In other words, the attacker must ask itself whether it would be reasonable to conclude that the intelligence was reliable enough to conduct the attack in light of the circumstances ruling at the time.
- The enemy’s intent may be based on specified preconditions prior to actual implementation of any existing plans. In such circumstances, these specified preconditions have to be fulfilled before the civilian object becomes a military objective by purpose. In other words, intelligence or other information has to lead to a reasonable conclusion that plans are in the process of being implemented, or will be implemented in the near future. Two examples can be given: (i) Communication intercepts or other intelligence may reveal that certain civilian airfields have been designated as alternative recovery airfields in the event that a military airfield is unusable. Once the military airfield is unusable, the designated alternative recovery airfields become military objectives by purpose and may be attacked, regardless of their actual or ultimate use; (ii) Overt contingency plans may exist for the use of certain civilian objects (such as civilian transports) for military airlift purposes. As long as no action is taken to activate the civilian transports for these purposes, they remain civilian objects. However, upon activation for military service, the transports in question become military objectives by purpose, regardless of their actual or ultimate use.
- This criterion requires actual use by the enemy of a particular object that, on the face of it, is civilian in nature. In other words, the object is not a military objective by nature, but subsequently becomes a lawful target as a result of conversion to military use.
- For instance, a purely civilian airfield that is subsequently used to launch or recover military aircraft loses its civilian character and becomes a military objective for the duration of its military use. Other examples would relate to (i) enemy troops billeted in a civilian hotel or school; (ii) enemy use of a civilian broadcast facility for military transmission; or (iii) civilian vehicles being commandeered by enemy forces to transport troops or materiel.
- In all such instances, the civilian objects become military objectives through use and may be attacked, subject to the principle of proportionality (see Rule 14) and Section G. They may not be attacked prior to such use unless there is sufficient evidence of the enemy’s intent to use the object for military ends (thereby qualifying under the purpose criterion, see Rule 22 (c)).
- Once use for a military purpose ceases, the object ceases to be a lawful target and may no longer be attacked. That said, if there is reliable intelligence that the enemy intends to use the object again in the future, it may remain a military objective, albeit by purpose, rather than by use. However, the mere fact that an object was used once as a military objective does not suffice, in and of itself, to establish purpose for future use.
- Any civilian object may become a military objective through use, including those entitled to specific protection but abused by a Belligerent Party through military use (see Sections K-N). Even objects entitled to specific protection, such as medical units (see Section K) or cultural property (see Section N (II)) can become military objectives if so used. In such a case, see Rule 32 (a) as well as Rule 35 (a) and Rule 35 (b).
- In case of doubt as to whether an object which is ordinarily dedicated to civilian purposes is being used for military purposes, it may only be attacked if, based on all the information reasonably available to the commander at the time, there are reasonable grounds to believe that it has become and remains a military objective (see Rule 12 (b)).
- Any military use of a civilian object renders it a military objective. However, the fact that it has become a military objective by use does not exclude the possibility of simultaneous civilian use. Such objects are commonly referred to as “dual-use” objects. Despite the fact that they have become a military objective, the decision whether or not they can be attacked depends by and large on the application of the principle of proportionality (see Rule 14). The classic example in the context of air or missile operations is an airport used both by military and civilian aircraft.