Ukraine Symposium – Destructive Counter-Mobility Operations and the Law of War

Decades of experience have greatly improved familiarity with, if not always fidelity to, law of war rules applicable to attacks on enemy forces. Less well appreciated is the law of war regime applicable to other acts of violence including destruction or demolition of objects in circumstances that do not immediately involve enemy forces. As the international community investigates potential war crimes committed in Ukraine, it’s worth recalling how the law differentiates attacks against enemies from mere destruction or demolitions conducted out of contact with enemy forces, a point fine in fact but fundamental in law.

Defensive Destruction in Ukraine

In the earliest stages of the Ukraine-Russia conflict, Ukrainian forces carried out destructive defensive preparations that involved widespread damage to Ukrainian property and infrastructure. The purpose of these acts was to obstruct the path of Russian forces or to prevent their offensive use of infrastructure.

One of the earliest such acts involved the 25 February destruction of a bridge over the Teteriv River, 30 miles north of Kyiv. Another report identified a claim by the Ukrainian General Staff that a military engineer was killed when he heroically detonated explosives while still on a bridge in the Kherson region to slow an imminent Russian advance. Loss of bridges has reportedly driven Russian forces to resort to time-consuming diversions or to pontoon bridging operations, which have been foiled by Ukrainian attacks.

Ukrainian forces have built other obstacles along likely avenues of advance. They have emplaced so-called Czech hedgehogs, salvaged steel beams welded together at odd angles, to slow tanks. More destructively, trees have been hastily felled across roads to block Russian movement.

Meanwhile, by early March, reports and images of extensive flooding north of Kyiv along the Dnieper River emerged. Accounts of the cause of flooding vary, but some sources claim that Ukraine deliberately released the waters to slow the advance of Russian ground forces. While no doubt damaging to Ukrainian infrastructure, flooding may have contributed to the now infamous miles-long back up of a Russian armored column and saved the city of Kyiv.

Defensive preparatory destruction has been a regular part of warfare since ancient times. A recent study estimates that one-third of floods in a region of the Netherlands between the years 1500 and 2000 were a result of military strategic flooding. Thought to be the largest scale act of defensive destruction, in 1938 Nationalist Chinese forces breached levees along the Huang He River to slow a Japanese advance. The resulting flooding, famine, and disease is estimated to have cost as many as 800,000 lives.

Despite radical changes in warfare across the ages, military doctrine has consistently advised defenders to resort to destruction to impede invasions and assaults. Current U.S. military doctrine prescribes a wide range of defensive and preventive preparations, many of which involve widespread destruction of objects, natural resources, and property.  Joint Publication 3-15, Barriers Obstacles, and Mine Warfare for Joint Operations lists a number of obstacles that are used in defensive operations including demolition obstacles “created by the detonation of explosives.” Some examples include bridge demolitions, road craters, and abatis. Their purpose is to counter enemy mobility or to channel movement into an engagement area for later targeting. Effective employment of demolition obstacles offers a compelling military advantage to the defending force.

Attacks Distinguished

In relative terms, targeting law—the body of rules applicable to attacks during the conduct of hostilities—is among the more refined regimes of the law of war. Treaties and customary international law include extensive restraints on targeting operations. These include very basic rules such as the requirement to distinguish lawful targets from protected civilians and civilian property. They also include important definitions such as those of civilian persons and of military objectives. Targeting law also prescribes highly elaborate rules including, among others, a finely-wrought regime of precautionary measures that must be undertaken prior to and during strikes.

While perhaps eye-catching as prescriptions for the military operations generally, targeting rules lie behind an important threshold of application. In both its conventional and customary incarnation, targeting law applies only to operations that amount to attack.

Article 49 of Additional Protocol I to the 1949 Geneva Conventions (AP I) defines attacks as “acts of violence against the adversary, whether in offence or in defence.” This definition is widely regarded as customary and therefore applies to all States.

But it is also clear that only violence directed at an enemy implicates the rules applicable to attack. In fact, at the diplomatic conference that adopted Article 49, States convincingly rejected a proposal to broaden the concept of attack by deleting the phrase “against the adversary” from its agreed definition (para. 1877). Therefore, violent acts resulting in destruction or damage conducted out of contact with an enemy or against objects under a force’s own control do not amount to attacks for purposes of targeting law. The legal upshot is to exempt these operations from the targeting law regime.

True, AP I intermingles into targeting law other protections applicable to non-attack operations, such as the requirement that “[i]n the conduct of military operations, constant care shall be taken to spare the civilian population, civilians and civilian objects.” But the term attack remains a critical definitional threshold for much of targeting law, appearing consistently in expressions of targeting rules. Applying targeting rules to operations short of attack amounts to fundamental legal error.

Turning to the present conflict, although undoubtedly violent acts, many of Ukraine’s destructive defensive preparations are likely not regulated by targeting law. Because most of Ukraine’s preparatory demolition of bridges was conducted against its own property, not controlled by enemy forces, it is unlikely those operations amounted to attacks in the legal sense. Ukraine’s destruction of most bridges preceded their use or capture by Russian forces. Additionally, although directed to accomplish the legitimate military objective of slowing enemy advance, Ukrainian flooding operations were not carried out in contact with enemy forces, were not directed at the enemy itself, and were not directed at objects belonging to or controlled by Russia. Therefore, they do not cross the attack threshold that activates rules applicable to targeting operations.

The concept of attack features in international criminal law as well. By comparison, however, international criminal law uses the term attack more broadly. For instance, Article 8 of the Rome Statute of the International Criminal Court (ICC) identifies war crimes including “[i]ntentional attacks against …” a variety of persons and objects seemingly without regard to their relationship to an adversary.

Debate over the legal significance of the term flared recently at the ICC. An appeals chamber of the Court addressed the extent to which the Rome Statute’s use of the term “attack” should be equated with the targeting law concept of attack but did not produce an unequivocal answer. The Court’s judgment was at best a “stalemate” on the definition of attack under the Statute leaving its meaning for purposes of the Rome Statute unclear. Articles of War hosted a series of posts that addressed both sides the ICC attack question in the context of criminal enforcement against individual persons.

At present, the soundest practical approach is to equate the meaning of attack between the law of war and the international criminal law instruments that enforce it. But the issue is certainly ripe for expressions of opinio juris (a sense of legal obligation) by States.

Destruction Distinguished

Failure to qualify as attack does not render an operation unregulated, however. The law of war includes elaborate regulatory regimes applicable to a broad range of military operations short of attack, including but not limited to internment, interrogation, requisition, confiscation, evacuation, and spying. The most significant difference between these non-attack-related regimes and the law of targeting may be that the former regimes generally do not preclude directing efforts at civilians and civilian objects. Although significant limits and treatment obligations apply, belligerents may intern civilians, they may requisition civilian property, and they may collect information on civilians consistently with the law of war.

Alongside its regulation of other non-attack operations, the law of war addresses destruction most directly in Regulations annexed to the 1907 Hague Convention IV. Article 23 indicates “it is especially forbidden … [t]o destroy or seize the enemy’s property unless such destruction be imperatively demanded by the necessities of war” (para. g). Meanwhile, the 1949 Geneva Conventions address destruction in the context of belligerent occupation, prohibiting it “except where such destruction is rendered absolutely necessary by military operations.” The Conventions also include “extensive destruction … of property, not justified by military necessity and caried out unlawfully and wantonly” as a grave breach. And the ICC Rome Statute enumerates a war crime nearly identical to the Hague Regulations Article 23 expression.

Military necessity is the operative limit on demolitions or destruction of property outside the context of attack. It is a notoriously vague standard. A widely shared elaboration advises, “Military necessity may be defined as the principle that justifies the use of all measures needed to defeat the enemy as quickly and efficiently as possible” (§ 2.2) (emphasis in original). Another influential source indicates, “Military necessity is now defined as “the principle whereby a belligerent has the right to apply any measures which are required to bring about the successful conclusion of a military operation and which are not forbidden by the laws of war” (§ 2.2).

But the Hague Regulations’ reference to destruction that is “imperatively demanded” likely indicates a heightened necessity standard. In that sense, bare necessity is insufficient to justify destruction of property; the fact that destruction is merely useful or conducive to military success would not justify it. Under this view imperative demand would likely require that no other option or act short of destruction be available to a belligerent to achieve a given war aim— in other words, the belligerent is compelled under the circumstances to destroy the object. Because destruction is often irreversible, prudence likewise counsels a heightened necessity standard for destruction. The U.S. Department of Defense Law of War Manual appears to adopt such a heightened view of necessity with respect to destruction. The Manual notes that when law of war instruments refer to absolute or imperative necessity, “military necessity must not be conflated with mere convenience” (¶ (emphasis in original).

Despite its apparent demand for a heightened showing of necessity, the law of war destruction standard reflects in many senses a less demanding legal standard than its counterpart applicable to attack operations. First, and foremost, the destruction standard admits operations directed at civilian property. As distinct from operations that amount to attack, destructive operations that do not amount to attack are not limited to military objectives. Attacks may only be directed against objects that make an effective contribution to military action such that if destroyed they offer a definite military advantage. While the necessity component of the latter prong seems encompassed by the destruction rule’s reference to imperative demands of military necessity, the former effective contribution prong is not. To destroy an object under his own control, a commander need not articulate how that object has been or imminently will make an effective contribution to enemy action.

Second, the destruction standard does not feature an expressed proportionality component. The law of war rules that expressly forbid or require cancelation of attacks expected to cause harm to civilians and civilian objects that is excessive in relation to anticipated military advantage lie behind the targeting law attack threshold. Only if one regards proportionality as either an uncodified rule of custom applicable to all military operations or if one regards the overarching principle of proportionality (§ 2.4) to have a rule-like effect, can one say that proportionality calculations are required for mere destruction or demotion of objects.

Third, and related, the destruction rule does not feature the elaborate procedural measures of precaution that are an increasingly emphasized aspect of targeting law. While attacks must be preceded by warnings when feasible, by feasible efforts at target verification, including for Parties to AP I a presumption of civilian status, and by feasible measures to minimize harm to civilians and civilian objects, no similar precautionary measures are explicitly required by the destruction rule.

All the same, the heightened necessity component of the destruction rule surely carries some inherent or implied obligations of a procedural nature. That is, to determine whether destruction is indeed imperatively demanded, a belligerent must identify a specific military advantage to be gained, must make a reasonable effort to determine the measures available to secure that advantage, and must conclude that destruction is required, or perhaps, the only way to achieve the required effect on the enemy.

Finally, the Hague Regulations destruction standard is notable for its limited scope of application. By its terms, it only applies to operations against enemy property. That term most clearly encompasses objects belonging to an adversary belligerent and its population. The rule does not reach destruction of a belligerent State’s own property or of property belonging to its population. Similarly, destruction of a property belonging to a co-belligerent or neutral State’s property or property of its citizens does not fall within the ambit of the rule. The rule’s enemy-friendly distinction presumably rests on an assumption that other legal regimes including municipal law, the law of neutrality, and general public international law regulate destruction of the property not belonging to an enemy belligerent.

Some military legal doctrine papers over the attack-destruction distinction. For example, U.S. legal doctrine advises that applying attack rules to destructive acts that do not amount to attack may provide commanders and their soldiers effective legal top cover (§ The U.S. view appears to conclude that any destruction of property that satisfies the more restrictive targeting law regime would necessarily meet the comparatively permissive military necessity standard strictly applicable to demolition or destruction. The Manual observes, “if sufficient military necessity exists to justify attacking an object as reflected by that object meeting the definition of military objective, then imperative military necessity would also exist to justify seizing or destroying that object measures short of attack” (§ While perhaps a useful measure to guarantee legal compliance, it should be emphasized that such doctrinal policies cannot alter the applicable legal landscape. Enforcement efforts, such as those underway with respect to the Ukraine conflict, must apply the prevailing law of war attack-destruction distinction, including its comparatively stark necessity requirement, carefully and rigorously.


In sum, destruction of a belligerent’s own property, public or private, when out of contact with enemy forces does not implicate the targeting law regime of the law of war. A belligerent’s destruction of enemy property while out of contact, and not in the status of an occupying power, is expressly regulated by the Hague Regulations Article 23(g) imperative military necessity standard.

Ukraine’s extensive defensive operations undertaken to prevent Russian advances, and their apparent effectiveness, confirm the important role that defensive destruction and demolitions conducted out of contact with enemy forces continue to play in armed conflict. While the extensively destructive and violent nature of these operations may reflexively or intuitively attract analysis under the law of targeting, the law of war includes a distinct, though comparatively less-developed, legal regime applicable to destruction that does not amount to attack on an enemy force. That regime applies only to destruction of enemy property and prohibits all destruction not imperatively demanded by military necessity.

To the consternation of some, to the comfort of others, many law of war rules are highly ambiguous. By comparison with the carefully honed regime of modern targeting law, law of war provisions applicable to defensive destruction present an admittedly indeterminate regime of rules, governed at its essence by the notoriously vague, and often morally fraught concept of military necessity. But, far from an oversight or “gap” in the law, the attack-destruction distinction appears to have been a deliberate calculation by States. The vital and highly commendable work of enforcing the law of war in the Ukraine context is well-advised to apply the attack-destruction distinction carefully.


Sean Watts is a Professor in the Department of Law at the United States Military Academy, Co-Director of the Lieber Institute for Law and Land Warfare at West Point, and Co-Editor-in-Chief of Articles of War.

COL Winston Williams is Head of the Department of Law at the United States Military Academy, Co-Director of the Lieber Institute for Law and Land Warfare at West Point, and Co-Editor-in-Chief of Articles of War.



Photo credit: Lukáš Malý