Ukraine Symposium – Retaliatory Warfare and International Humanitarian Law

On 29 December, Russia launched a massive country-wide drone and missile assault on Ukraine. Although Ukraine shot down 114 of the 158 inbound missiles, over 40 Ukrainian civilians died in the attacks, and more than 160 were wounded. In addition to military objectives, targets included hospitals, residential areas, schools, and other civilian infrastructure. It was one of the most intense Russian aerial bombardments since the beginning of the war.

In response, President Zelensky warned that Ukraine would “work towards pushing the war back to these human scum where it came from – home to Russia.” Ukraine made good on that threat the following day by attacking the Russian city of Belgorod, near the Ukrainian border. Russian authorities maintain that the attacks and falling debris from intercepted rockets and missiles killed over 20 and injured nearly 110 civilians. It was the deadliest Ukrainian attack on Russian territory ever.

Ukrainian sources have stated that the intended targets were military, although video of the strikes shows explosions in what appear to be residential and commercial areas of the town (see also here and here). Russia’s Ministry of Defense (MoD) labeled the attacks “indiscriminate” and announced that they would “not go unpunished.” Russian forces promptly carried out the threat by retaliating that same day with attacks on nearby Kharkiv, Ukraine’s second-largest city. Despite the Russian MoD’s claim that it used high-precision weapons against military targets, the attacks damaged residences, a major hotel, stores, and a medical facility and injured at least 28 civilians. Russian forces also reportedly shelled a village, killing three, and continued attacking other population centers elsewhere on New Year’s Day.

In an extraordinary see-saw week, the UN Security Council met twice, first on the 29th to consider Russia’s attack and then, at Russia’s request, the next day to discuss Ukraine’s response. At the latter meeting, the U.S. Political Minister Counsellor called for “the protection of all civilians, on all sides, of every conflict” but did not address the Ukrainian operations directly. His British counterpart went further, arguing, “If Russia wants someone to blame for the deaths of Russians in this war, it should start with President Putin.”

The Russian Permanent Representative engaged in his by now tired denial of blame, observing,

It was just yesterday that we met in this room at the insistence of representatives of the Kiev regime and their sponsors, who tried to pass off the consequences of the unprofessional work of Ukrainian air defense forces as deliberate strikes by the Russian troops against residential areas in Ukrainian cities.

He claimed that “what we saw was not a strike against military facilities with possible consequences for the civilian population, but a deliberate act of terrorism directed against civilians,” and alleged that “Brussels, along with Washington and London, as well as the majority of EU countries, are complicit in the crimes committed by the Kiev clique.”

This exchange begs the question of whether retaliatory strikes during an armed conflict are lawful, the subject of this post. I will first dispense with two red herrings relevant to the exchange. The piece then turns to the circumstances in which retaliation is permissible under international humanitarian law (IHL) and those in which it is not. I conclude with some thoughts on retaliatory warfare.

Red Herrings

Before turning to the relevant law, dispensing with two red herrings is helpful. First, as noted by the UK representative at the Security Council, no Russian would have died had Putin not ordered an armed attack on Ukraine in violation of the prohibition on the use of force in UN Charter Article 2(4). While factually accurate, that body of law (jus ad bellum) is distinct from the IHL that governs Ukraine’s attacks on Belgorod. By the “principle of equal application,” IHL applies equally to all parties to a conflict. Thus, Russia’s clear violation of the jus ad bellum and Ukraine’s manifest right of self-defense under UN Charter Article 51 in no way justifies any deviation from IHL rules by the latter.

Second, the fact that Ukraine launched the attack into Russian territory is of no legal significance. Despite the concern of some States supporting Ukraine, including the United States, that operations on the territory of Russia might escalate the conflict, hostilities during an international armed conflict are permissible as a matter of law anywhere in a belligerent State and in the commons (international waters, international airspace, outer space). The issue of strikes on Russian territory is geopolitical in nature, not legal.

The Law

Nearly two years into this “hot” phase of the war, it is undeniable that Russia has embraced a strategy of targeting civilian population centers to bring Ukraine to its knees. Its attacks are classic examples of directly targeting civilians and civilian objects, a so-called “internationally wrongful act” under the law of State responsibility by Russia, and war crimes by those who planned, approved, and (in many cases) executed them. To suggest Russia has suddenly limited its aerial campaign to military objectives is farcical.  

Therefore, the question on everyone’s mind is the lawfulness of the Ukrainian response. The answer depends on whether Ukraine was attacking military objectives, as claimed (with videos such as here and here reflecting strikes missing lawful targets or causing collateral damage), or was instead intentionally targeting the civilian population center of Belgorod.  

As a general matter, attacking targetable persons (combatants and civilians directly participating in hostilities) and striking military objectives in retaliation for the enemy’s operations (wrongful or not) is lawful. The fact of a retaliatory motive is simply irrelevant; the legal issue is whether the side undertaking the retaliation complied with the rule of proportionality and the obligation to take precautions in attack (Additional Protocol I, (AP I) arts. 51 and 57; U.S. DoD Law of War Manual, § 5.10 – 5.12; International Committee of the Red Cross (ICRC) Customary IHL study, rule 14 and ch. 5). Concerning the Ukrainian attacks, it is currently impossible to offer an opinion on proportionality because we do not know the targets (anticipated military advantage), and equally impossible to assess compliance with the precautions obligation without knowing more about the weapons and weapons systems used and otherwise available, or how tactics could have been adjusted to avoid civilian harm (e.g., timing and alternative targets to achieve comparable effect).

But what Russia alleges and what some may suspect is that following one of the deadliest Russian attacks on its cities, Ukraine launched a tit-for-tat response directed at a civilian population center. Such an attack would violate the AP I, Article 51 prohibition on attacking the civilian population, and the Article 52 prohibition on attacking civilian objects and their customary law counterparts (see ICRC Customary IHL study, rules 1, 2, 7).

As a general matter, the fact that Russian operations have systematically and with great frequency violated IHL has no bearing on the lawfulness of the Ukrainian response. One side’s violations of the law do not relieve the enemy of its obligation of compliance. This rule appears in Article 51(8) of AP I, which binds both Russia and Ukraine as Parties to the instrument: “Any violation of these prohibitions shall not release the Parties to the conflict from their legal obligations with respect to the civilian population and civilians, including the obligation to take the precautionary measures provided for in Article 57.” In my estimation, it also reflects customary law.

There is one exception to the customary rule – the right of belligerent reprisal. A reprisal is an operation by one side of the conflict that would violate IHL, but for the fact that it is designed to compel the enemy to end its own violation(s). Importantly, it is not available to respond to jus ad bellum breaches like Russia’s unlawful use of force against Ukraine; it is only permissible in response to the enemy’s IHL violations.

It is also subject to strict conditions. These include: 1) a purpose of compelling the enemy to refrain from further violations, with a likelihood that it will do so as a result of the reprisal; 2) exhaustion of viable lawful alternatives; 3) warning and public announcement in order to facilitate reprisal’s coercive purpose; 4) proportionality to the violations to which it responds; 5) approval at the highest levels of government; and 6) discontinuance as soon as the enemy stops violating IHL (see U.S. DoD Law of War Manual, § 18.18; ICRC Customary IHL study,  rule 145).

The 1949 Geneva Conventions, which reflect customary law (ICJ, Nuclear Weapons advisory opinion, para. 79), forbid certain reprisals. These include reprisals against those who are hors de combat, medical and religious personnel, medical units and facilities, hospital ships, and prisoners of war (see U.S. DoD Law of War Manual, § 18.18.3.2 and associated citations). Certain treaty obligations supplement these prohibitions for States that are Party to them. They include a ban on using mines, booby-traps, and other such devices against civilians and civilian objects (CCW Protocol II, art. 3(7)); reprisals against cultural property (Cultural Property Convention, art. 4(4)); and reprisals directed at objects indispensable to the survival of the civilian population, the natural environment, dams, dykes, and nuclear electrical generating stations (AP I, arts. 54-56).

In this case, the central issue is civilians and civilian objects. Some experts suggest that reprisals against them may now prohibited by customary law. That is a difficult case to make considering, inter alia, the consistent opposition to that proposition from some States, including the United States.  However, reprisals are prohibited for States that are Party to AP I.

Article 51(6): Attacks against the civilian population or civilians by way of reprisals are prohibited.

Article 52(1): Attacks against the civilian population or civilians by way of reprisals are prohibited.

A few States issued understandings and reservations bearing on these prohibitions at the time of ratification (e.g., Egypt, France, Germany, Italy). The United Kingdom’s reservation is the most direct.

If an adverse party makes serious and deliberate attacks, in violation of Article 51 or Article 52 against the civilian population or civilians or against civilian objects, or, in violation of Articles 53, 54 and 55, on objects or items protected by those Articles, the United Kingdom will regard itself as entitled to take measures otherwise prohibited by the Articles in question to the extent that it considers such measures necessary for the sole purpose of compelling the adverse party to cease committing violations under those Articles, but only after formal warning to the adverse party requiring cessation of the violations has been disregarded and then only after a decision taken at the highest level of government. Any measures thus taken by the United Kingdom will not be disproportionate to the violations giving rise thereto and will not involve any action prohibited by the Geneva Conventions of 1949 nor will such measures be continued after the violations have ceased.

As Russia and Ukraine are States Party to Additional Protocol I, and neither has issued a comparable reservation, if Ukraine targeted Belgorod generally or individual civilian entities therein, it violated IHL. Further, even if that was the case, Russia’s response against Kharkiv and other locations could not be justified as a lawful reprisal of its own in response to the Ukrainian strikes.

Yet, it is essential to understand the ramifications of the discussion above. If a State like the United States that is not Party to Additional Protocol I had mounted operations analogous to Ukraine’s and complied with the conditions described, it would not have violated IHL. The same is true regarding a State that is a Party to the Protocol but is at war with a non-Party, at least until the prohibitions become customary.

Retaliatory Warfare

Retaliation against lawfully targetable persons and military objectives can serve valuable purposes during an armed conflict. It can demonstrate resolve to the enemy, one’s own public, and the international community. Retaliation can also enhance the morale of one’s forces and weaken that of the enemy. This is, of course, not always the case, for retaliation can also cause an escalation of an armed conflict and, in that regard, serve as an obstacle to its termination. But generally speaking, retaliating, even robustly, often makes operational and strategic sense.

However, reprisals are seldom beneficial, even though they are in response to the enemy’s underlying unlawful conduct. This is why States have accepted treaty limitations on reprisals, engaged in the practice and opinio juris necessary for some reprisal prohibitions to crystallize into customary law, and imposed stringent conditions on conducting them.

Beyond the law, there are sound operational and strategic reasons for refraining from reprisals in those limited cases where they are lawful. The U.S. DoD Law of War Manual points out that the tactic can: 1) divert military resources from operations that may be more effective; 2) negatively affect the attitudes of neutral States; 3) strengthen the enemy’s morale; 4) risk an escalatory spiral; and 5) affect the enemy’s capability to rehabilitate an area once the conflict is over (U.S. DoD Law of War Manual, § 18.18.4).

I would add that although meant to restore a situation to one of compliance with IHL, reprisals may have the opposite effect of engendering broader disrespect for the law. Additionally, engaging in unlawful operations, even if permissible as a reprisal, can negatively affect the morale and discipline of one’s own forces and result in a loss of public support, especially given that the battlespace is ever more transparent. I can imagine very few situations in which reprisals make sense.                   

Concluding Thoughts

The Russian attacks on populated areas have been, and remain, unlawful; claims to the contrary are absurd. And it is too early to tell whether Ukraine resorted to the tactic of population centers over the weekend. But the bellicose statements by Ukrainian officials combined with widely circulating video footage and the extent of civilian casualties arguably merit further investigation.

If Ukraine has done so, its operations violated obligations regarding targeting population centers and civilian objects under Additional Protocol I. And because that treaty bans reprisals, Ukraine may not avail itself of the customary law right to take certain highly restricted reprisals.

Finally, although States are not obligated to prove they complied with international law in particular operations, good sense dictates that Ukraine should attempt to address concerns about its actions. This is ever more important at a time when external support for Ukraine, including in the United States, is wavering. Its most vital asset in securing that support is the perception that it is the “good guy” while the Russians are the “bad guys.” Only through rigorous and transparent adherence to IHL can it retain that advantage.

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Michael N. Schmitt is the G. Norman Lieber Distinguished Scholar at the United States Military Academy at West Point. He is also Professor of Public International Law at the University of Reading and Professor Emeritus and Charles H. Stockton Distinguished Scholar-in-Residence at the United States Naval War College.

Photo credit: Dnipropetrovsk Regional State Administration