Attacking Dams – Part II: The 1977 Additional Protocols

by | Feb 2, 2022

Attacking Dams - Part II

A recent New York Times report of a 2017 attack by U.S. forces against the Tabqa Dam in Syria has sparked controversy and criticism. In Part I of this series, I described reports of that incident and examined the customary international humanitarian law governing dam attacks during international and non-international armed conflict. I concluded that although attacks on dams and persons or objects in their vicinity merit particular caution considering the potentially disastrous consequences of a dam breach for the civilian population, the same general targeting rules applicable to other attacks govern them.

In this installment, I consider the special protection dams enjoy during international and non-international armed conflict under 1977 Additional Protocols I and II, respectively. These instruments contain the first treaty provisions directly addressing attacks on dams. Earlier, the International Committee of the Red Cross (ICRC) had included an article on the subject (Article 17) in its 1954 Draft Rules for the Limitation of the Dangers Incurred by the Civilian Population in Times of War. However, States did not adopt those rules. In particular, they viewed the ICRC’s suggestion of immunity agreements for dams as impractical, especially during an armed conflict (see Bothe et al. Commentary, at 394).

Additional Protocols I and II do not bind the United States, but most of its NATO Allies and other key partners, like Australia, Japan, and South Korea, are Party to one or both. So too are potential adversaries, including China, North Korea, Russia, and Syria. Because legal interoperability in coalition operations requires an understanding of the legal constraints on all coalition members, U.S. judge advocates should grasp the nuances of this special protection with a fair degree of granularity.

Additional Protocol I and International Armed Conflict

In an international armed conflict, Additional Protocol I (AP I), Article 56 governs attacks conducted by the armed forces of States Party to that instrument against its enemy’s dams if the latter is also a Party to the Protocol. Violation of the rule by a State Party is a grave breach (AP I, Article 85), a characterization with important implications that are beyond the scope of this post.

Party status is a determinative matter in applying Article 56. For example, if a U.S. coalition partner is an AP I State but is conducting operations against a non-Party like Iran, the customary IHL discussed in Part I of the series is the governing legal regime, not Article 56. Of course, the partner may elect to apply the AP I rule as a matter of policy in such circumstances. Similarly, the United States could accept restrictions on its operations along the lines of Article 56 to facilitate operational consistency across the coalition. But doing so would be a matter of operational and policy, not legal, concern.

Article 56 is a highly detailed provision, the key parts (for our purposes) of which provide,

1. Works or installations containing dangerous forces, namely dams, dykes and nuclear electrical generating stations, shall not be made the object of attack, even where these objects are military objectives, if such attack may cause the release of dangerous forces and consequent severe losses among the civilian population. Other military objectives located at or in the vicinity of these works or installations shall not be made the object of attack if such attack may cause the release of dangerous forces from the works or installations and consequent severe losses among the civilian population.

2. The special protection against attack provided by paragraph 1 shall cease:

(a) For a dam or a dyke only if it is used for other than its normal function and in regular, significant and direct support of military operations and if such attack is the only feasible way to terminate such support;

(b) For a nuclear electrical generating station only if it provides electric power in regular, significant and direct support of military operations and if such attack is the only feasible way to terminate such support;

(c) For other military objectives located at or in the vicinity of these works or installations only if they are used in regular, significant and direct support of military operations and if such attack is the only feasible way to terminate such support.

3. In all cases, the civilian population and individual civilians shall remain entitled to all the protection accorded them by international law, including the protection of the precautionary measures provided for in Article 57. If the protection ceases and any of the works, installations or military objectives mentioned in paragraph 1 is attacked, all practical precautions shall be taken to avoid the release of the dangerous forces.

4. It is prohibited to make any of the works, installations or military objectives mentioned in paragraph 1 the object of reprisals.

5. The Parties to the conflict shall endeavour to avoid locating any military objectives in the vicinity of the works or installations mentioned in paragraph 1. Nevertheless, installations erected for the sole purpose of defending the protected works or installations from attack are permissible and shall not themselves be made the object of attack, provided that they are not used in hostilities except for defensive actions necessary to respond to attacks against the protected works or installations and that their armament is limited to weapons capable only of repelling hostile action against the protected works or installations.

If no military objective is the object of attack, the AP I, Article 52, prohibition on attacking civilian objects would bar attack altogether. Article 56 only applies when either the dam qualifies as a military objective or there are military objectives on or near it. The Korean War strike on the Hwachon hydroelectric dam complex exemplifies an attack on a dam that qualifies as a military objective during an international armed conflict. U.S. Navy aircraft struck the dam in 1951 because North Korea could use it to block the advance of U.N. forces by flooding the valley downstream. North Korea could also close the dam’s gates to lower the downstream water level, thereby making river crossing possible to attack the U.N. forces’ flanks.

In customary international law, a dam that qualifies as a military objective may be attacked subject to the rule of proportionality and the requirement to take precautions in attack (these rules also appear in Articles 51, 52, and 57 of Additional Protocol I).  However, Article 56 goes further. It bars attack despite full compliance with these rules. In other words, it imposes an absolute standard, not a relative one like the proportionality rule. Yet, it does so in a somewhat limited fashion.

First, unlike the customary rule on attacking entities containing dangerous forces (see Part I), Article 56 is limited to three target sets—dams, dikes, and nuclear electrical generating stations. The standard targeting rules in Additional Protocol I would govern a strike on any other target containing dangerous forces. For instance, an attack against a factory that might release toxic chemicals would not be subject to Article 56. The limitation to these three target sets was intentional; indeed, several States unsuccessfully pushed for broader coverage, such as inclusion of oil storage facilities.

Second, Article 56 only applies to “attacks,” a term of art in IHL. It would not bar the destruction of a Party’s own dam, for instance, to flood a potential avenue of attack by the enemy. Use of the term “attack” instead of “destruction” was intended to make this distinction clear-cut (Bothe et al. Commentary, page 396).

Third, the prohibition only applies to situations in which the release of the dam’s water causes losses among this civilian population. If civilians are injured or killed at or near the dam during the attack instead of due to the water’s release, the standard targeting rules apply. For instance, if an attacker decides to use anti-personnel or other weapons unlikely to cause a breach of the dam, Article 56 would not apply even if many civilians would likely be killed.

Fourth, the potential harm that bars attack is “severe losses among the civilian population.  Standard targeting rules govern an attack causing harm to the population below the severe threshold. The ICRC’s Article 56 Commentary defines severe as “important” or “heavy,” which is not particularly useful. But the Commentary acknowledges as much by pointing out that the “concept is a matter of common sense and it must be applied in good faith on the basis of objective elements such as the proximity of inhabited areas, the density of population, the lie of the land etc.”

Unsatisfactory as this may appear, it is not uncommon for IHL rules to express vague thresholds, perhaps most notably that barring “excessive” incidental injury and collateral damage in the proportionality rule that undergirds the customary law on attacking dams. And some cases are undeniably severe, as in the RAF’s World War II attacks against the Möhne and Eder dams, the breaching of which led to 1,300 deaths in Germany’s Ruhr Valley. Others are not, as in destroying a dam in a remote area when there is little risk of downstream harm to civilians.

Fifth, only harm to the civilian population triggers the prohibition. The severity calculation does not consider severe damage or destruction of civilian property. This conclusion derives from the AP I reference to civilians and civilian objects in both the proportionality (Article 51 and 57) and precautions in attack (Article 57) rules, but the absence of any reference to civilian objects in Article 56. Therefore, damage to or destruction of civilian objects downstream is subject to the same protection enjoyed by civilian objects elsewhere.

Sixth, Article 56(2) provides that the prohibition does not apply in certain circumstances where military necessity justifies attack, as in the case of a dam that is being regularly used to provide significant and direct support to enemy military operations and the only way to counter those operations is to mount an attack against the dam. The ICRC Commentary offers the paradigmatic example, “a road across the top of a dam which could, in combat conditions, become an essential route for the movement of armed forces.” Standard targeting rules apply in these cases. Moreover, in addition to the precautions in attack rules set out in Article 57 of AP I, an attacker also must do everything feasible to avoid releasing the waters. This is an unconditional requirement that is not tied to avoiding harm to civilians or civilian objects.

As with the term “severe,” the three regular, significant, and direct conditions are subject to interpretation. The ICRC’s Article 56 Commentary admits that the “triple qualification … may seem to be subject to subjective interpretation,” but notes, “these terms merely express common sense, i.e., their meaning is fairly clear to everyone. They need to be interpreted in good faith on the basis of objective elements.” Again, critics may lament the terms’ imprecision, but imprecision is a common trait of IHL.

Should an operation fall within the ambit of Article 56 despite these limitations, the article restricts operations against a dam or military objectives in the dam’s vicinity to an extent greater than customary law. It does so in two important ways. Most importantly, it prohibits an attack even when the anticipated military advantage of striking the dam or targets in the dam’s vicinity is so great that the expected incidental injury and collateral damage is not “excessive” relative to it (the proportionality threshold), and attack is the only means of achieving that advantage. In other words, if Article 56 is triggered, compliance with the proportionality and precautions in attack rules no longer permits attack.

Additionally, Article 56 appears to impose a lower standard of certainty of harm than is the case with the proportionality rule. The latter requires consideration of “incidental loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof” that “may be expected.” By contrast, Article 56(1) is triggered if an attack “may cause the release of dangerous forces.”

It would be overbroad to interpret the “may cause” text as denoting any possibility whatsoever. This is clear from the Bothe, Partsch, and Solf Commentary (they were participants in the Diplomatic Conference that drafted the Protocols), which notes that the drafting Committee elected to use “may” in lieu of “is likely” to raise the “standard of care to situations where the release of dangerous forces is objectively foreseeable rather than limiting it to cases where such effect is probable” (page 365). But the Article 56 standard certainly appears less demanding than that residing in the proportionality rule; the former would appear earlier along the uncertainty continuum than the latter (on targeting uncertainty, see here).

Seventh, and finally, like medical facilities, Parties to the conflict are permitted to station troops and military equipment at a dam to guard it, for example, against saboteurs. They may not be attacked so long as they only act defensively and are only armed to the extent necessary to counter attacks on the dam. The prohibition applies even if an attack against them would not risk causing the release of water. The ICRC’s Commentary helpfully illustrates the protection.

If the works or installations are at a distance from the combat area, it is mainly a matter of defending them against attacks mounted by combatants who have been infiltrated or parachuted, or against attacks by guided missiles or projectiles dropped from aircraft. Thus there will be needed, on the one hand, a military guard equipped with light individual weapons, and on the other hand, anti-aircraft artillery. In the second case such artillery may only be used against aircraft which are out to attack the protected works or installations, but not against aircraft flying over the works or installations on their way to attacking another military objective. It cannot be denied that this could pose serious difficulties of judgment.

If the works or installations are located within the combat area, the military guard and the anti-aircraft artillery protecting them will of course be part and parcel of the total military system, and it will be difficult to make a clear distinction between military deployments designed to defend the works and installations and other troops fighting in the area.

Of course, as the ICRC notes in the second paragraph, it may be difficult to distinguish between those guarding the dam and other personnel in the target area. Be that as it may, certain personnel and equipment on or near the dam enjoy special protection under Article 56.

The United States has long opposed Article 56. During a well-known presentation in 1987, then Deputy State Department Legal Adviser Michael Matheson explained,

the United States military based its objections on a pragmatic, real-world estimation of the difference between the two situations. The military perceives that in international conflicts, many situations may arise where it is important to attack and destroy parts of an electric power grid, such as a nuclear or hydroelectric generating station. In internal conflicts, on the other hand, such a significant real-world need will not exist. Preserving the military option in international conflicts where such facilities are more likely to become an object of military attack, therefore, is very important.

The DoD’s Law of War Manual confirms that this remains the U.S. position (section 5.13.1).

Additional Protocol II and Non-international Armed Conflict

Article 15 of AP II governs dam attacks during non-international armed conflict for all parties so long as the treaty’s applicability threshold has been reached. This is a determinative point because the instrument, and therefore Article 15, only applies when the non-international armed conflict is against an organized armed group that exercises sufficient control over part of the State’s territory “as to enable them to carry out sustained and concerted military operations and to implement” the Protocol [AP II, Article 1(1)]. For non-international armed conflicts falling below that threshold, the customary law examined in Part I of the series governs dam attacks. As an example, if an organized armed group temporarily occupies a dam but does not control a wider swath of territory, Article 15 would not apply.

Article 15 is much simpler than its AP I counterpart. It provides, in its entirety,

Works or installations containing dangerous forces, namely dams, dykes and nuclear electrical generating stations, shall not be made the object of attack, even where these objects are military objectives, if such attack may cause the release of dangerous forces and consequent severe losses among the civilian population.

As is apparent, its text is identical to the first sentence of AP I, Article 56. Therefore, the discussion of the seven limitations applies mutatis mutandis to dam attacks by either the organized armed group or the State’s armed forces during qualifying non-international armed conflicts.

Yet, the remainder of Article 56 is missing. For instance, the text regarding other military objectives in the dam’s vicinity is absent; an attack on them would therefore be subject to standard targeting rules even if an attack on them risked breach of the dam. Of course, the proportionality rule would loom large in such a situation. Nor is there a prohibition on attacking personnel or equipment guarding a dam. Again, standard targeting rules would apply to an attack on them.

More importantly, there is no exception for circumstances in which a dam is being used to regularly and directly support military operations in a significant manner. As a result, Article 15 is more stringent than its international armed conflict counterpart. This seems strange, for States are generally much more hesitant to accept limitations on their handling of internal conflicts than is the case for conflicts with other States. However, the ICRC Commentary to the article confirms that this was the drafters’ intent; the prohibition was meant to be categorical.

The United States is not as concerned with Article 15 as it is with AP I, Article 56. For instance, after stating that the United States believes that neither provision reflects customary law, the Law of War Manual observes (section 17.7.1),

the Executive, in submitting AP II to the Senate for its advice and consent to ratification in 1987, did not recommend a reservation from or an understanding applicable to this provision of AP II based on an assessment that preserving the option to attack works or installations containing dangerous forces would not be as important in internal conflicts as preserving that option would be in international armed conflicts.

Nevertheless, the U.S. position today remains that Article 15 does not reflect customary law in non-international armed conflicts, a conclusion supported by the authors of the San Remo NIAC Manual (section 4.2.3) and the ICRC’s treatment of dam attacks in its Customary International Humanitarian Law study (see discussion in Part I).


In assessing the AP I and II rules regarding dam strikes, it is essential to remember that there may be instances of international and non-international conflict in which Parties to the instruments are not bound by the provisions thereof. This may be either because the State is engaged in an international armed conflict with a non-Party or because the non-international armed conflict has not reached a level of intensity that would trigger application of AP II.

Additionally, the various limitations on the applicability of both Articles 56 and 15 mean that even in conflicts during which these instruments are in play, attacks against dams or military objectives in their vicinity will only sometimes be governed by their terms. In many cases, therefore, a dam attack will be subject to IHL prohibitions, obligations, and restrictions that are de facto identical to those governing attacks by non-Party States such as the United States.


Michael N. Schmitt is the G. Norman Lieber Distinguished Scholar at the United States Military Academy. He is also Professor of Public International Law at the University of Reading, Strauss Center Distinguished Scholar and Visiting Professor of Law at the University of Texas, and Professor Emeritus at the United States Naval War College.