Removing Constraints on Support to Ukraine: No Silver Bullets

Overnight on 30 May, media reporting claimed that US President Joe Biden had apparently relaxed restrictions on the use of US weapons against targets in Russia. This followed Ukrainian President Volodymyr Zelensky voicing his frustration at the continued existence of such limitations. The issue has been given extra relevance by Russian forces based in Belgorod launching a new operation around Kharkiv, and has been taken up by the NATO Secretary-General and the NATO Parliamentary Assembly. Journalists and analysts have been left to parse the meaning and phrasing of every (ambiguous) sentence uttered by Western politicians on the subject.

Current Ukrainian Operations and Existing Constraints

The start point, on which everyone seems to be in agreement, is that it is both legitimate and legal for Ukraine to attack military targets on Russian territory. It is defending itself against a Russian attack and can respond under Article 51 of the UN Charter, having been engaged in an International Armed Conflict since 2014. Provided it acts in accordance with International Humanitarian Law, it has a wide range of targets from which to choose, including oil and fuel production facilities which, while they may have a civilian function, are also contributing to the Russian war machine – so-called ‘dual use facilities’. Added to this would be the airbases for long-range Russian bombers that have been launching strikes against Ukrainian infrastructure and other civilian targets; military production facilities; ammunition dumps and storage facilities for other materiel; and a variety of military bases including the Russian ports for the Black Sea Fleet.

The suggestion of caveats first appeared with the provision of sophisticated and mostly longer-range weapons that arrived in mid-2022 and early 2023, from multiple launch rocket systems (MLRS) like the US HIMARS and UK M270, to cruise missiles like the UK Storm Shadow and French SCALP. Biden stated at the time that HIMARS would not be used against targets in Russia, and it later emerged that technical alterations had been made to ensure this was not possible. Meanwhile, UK statements on the use of Storm Shadow heavily emphasised its use inside Ukraine (including areas illegally annexed by Russia, like Crimea), mirroring apparent restrictions on the use of UK M270. The overriding concern in these early debates was the risk of escalation involved in any Russian response to the provision of more sophisticated and more threatening weapons.

That debate continues to rage, with the benefit of two years’ observations on Russian rhetoric and actions, including strikes against Ukrainian civilian targets and growing suggestions of a Russian sabotage campaign inside Europe. But alongside the serious consideration of managing this escalation (or calling Russia’s bluff) should be a discussion on the military utility of – and possible targets for – such weapons. Ukraine is already running a deep strike campaign using drones against a range of targets, occasionally hitting Moscow itself, but more frequently striking refineries and production facilities. These attacks reduce supplies going directly to Russian forces, and also cut revenue used to fund the war. In addition, a campaign against bomber airfields has destroyed both long-range bombers and smaller fighter-bombers. Some of these attacks have used drones and have taken place at extreme ranges of over 1,000 miles, but there also appears to be an element of infiltration and ground sabotage against bases and rail links, including some over 3,000 miles from Ukraine. Finally, Ukraine’s use of both air and maritime drones against the Black Sea Fleet has sunk a number of ships and even threatened the port at Novorossiysk. What, then, would other weapons add?

The Value of Deep Strike

The answer is that the types of targets and the defences around them work against the drone programme. First, the drones used by Ukraine tend to be slow and have limited payloads. They use sheer numbers to get through to targets, and although they have very long ranges – it can be hard, especially in the face of Russian air defences – to get sufficient numbers through to cause major and long-lasting damage, especially against hardened targets or those under cover. Flight time can vary, but for long-distance targets is sufficient to give the Russians early warning, which necessitates Ukrainian mass or much closer (and riskier) infiltration operations. For the long-distance and relatively predictable targets, this may be enough, but Ukraine needs firepower that it can bring to bear rapidly and with little warning. This is where ATACMS – with multiple variants – comes into play, and it could provide a valuable weapon for striking airbases hosting both fighter-bombers and attack helicopters, as well as rear-area logistics and ammunition dumps. Depending on which variants have been provided, both cluster and unitary warheads have ranges of up to 190 miles, providing a threat to static locations, such as in Belgorod, Voronezh, Kursk and maybe even Lipetsk oblasts.

Longer-range air defence systems could also play a role, albeit with some significant risks involved. Russian bombers mostly launch their cruise missiles within Russian airspace, so the launching aircraft are outside the ranges of systems like IRIS-T (15 miles) or point defence like Starstreak (5 miles). The same is true of some aircraft launching glide bombs, which are currently being used to devastating effect both on civilian areas and Ukrainian forces on the front line. Some can be released from 25 miles away; in the north this can be done from Russia. They are almost impossible to intercept, and this can only be achieved at great cost with expensive missiles used for multiple incoming bombs. Ideally, launch aircraft would be caught on the ground, but as a fallback, a surface-to-air missile (SAM) system like Patriot – with a range of around 100 miles (depending on the target) – could be pushed closer to the front line to shoot down Russian aircraft before release. So-called ‘SAMbushes’ involve removing launchers from around infrastructure and putting them at greater risk of attack, but pose a challenge to Russian aircraft which currently fire from airspace where they believe themselves to be safe. There is some doubt over the extent to which this represents a ‘strike’ on Russian ‘territory’, but media reporting suggests there has been disquiet over the use of German systems, which at least indicates the expectation of some kind of existing constraint.

The new development which raises the question of a potentially unintended constraint being rendered nonsensical by changes on the ground is the Russian assault towards Kharkiv and the massing of forces over the border from Sumy. Up until now, the ‘close’ fight has largely been conducted unambiguously on Ukrainian territory. In the case of Kharkiv, the proximity to the border means that Russian assault forces have been able to mass and assemble inside Belgorod, and artillery fire from within Russia can reach Ukrainian forces along the front. Removing restrictions on ‘standard’ HIMARS and other MLRS systems, as well as standard Ukrainian tube artillery firing Western-supplied 152mm and 155mm ammunition, would allow the Ukrainians to at least strike massing Russian forces and conduct counter-battery fire against artillery situated just over the border. In the case of HIMARS it would allow the Ukrainians to out-range the equivalent Russian guns (although reporting has indicated there is effective Russian interference with guided projectiles).

Perhaps surprising by their absence from this priority list are the Storm Shadow and SCALP missiles. While these would be useful for arms dumps, command locations and logistics targets with protection against drones, their (publicly-acknowledged) range of around 160 miles means that the launch point for the Ukrainian aircraft carrying them comes uncomfortably close to Russian air defences if the target is deep within Russia. For this reason, both have been used on targets much closer to the front line, including in and around Crimea. The provision of German Taurus, with a slightly larger warhead and a range up around 300 miles, could make striking deeper targets in Russia much more feasible, or bring additional firepower to bear on targets further south around Crimea, including the Kerch Bridge, where Russian air defences have already been degraded.

Keeping the Russians Guessing

It is worth concluding with an acknowledgement of the military benefits of ambiguity and what a change in policy would not achieve. The public Western position around the use of such weapons has been hugely variable; UK Foreign Secretary David Cameron, for example, did not explicitly say UK-supplied weapons could be used in Russia, and many of the recent statements of support have been generic. Beyond the question of escalation management, it would be prudent to keep Russia guessing about what sophisticated weapons may or may not be used against its forces, because this poses dilemmas about what mix of air defence systems to deploy and what level of dispersal or early-warning systems may be necessary. We can assume that Storm Shadow (for example) has not yet been fired against a Russian target as no components have emerged from debris, but the potential exists if the right tone is struck. It may also be the case that, behind the scenes, some constraints have already been lifted. At sea, the UK has retrospectively claimed credit for the use of maritime drones against the Black Sea Fleet. Given the UK’s role, alongside others, in providing support to Ukrainian drone programmes, it is possible that a number of countries have already provided components for weapons that have struck Russian targets. The ambiguity over this support not only evades questions of escalation, but also provides few clues for Russia that would allow it to prepare countermeasures until after such weapons can be used.

Larger Challenges Remain

At the same time, caution should be taken not to see a change in policy as a panacea for Ukraine’s current challenges. The successful campaign against Russian energy infrastructure has not forced Russia to reassess its campaign overall. The long-range bomber force has had to disperse and has reduced its strike capabilities, but has not ended attacks on civilian infrastructure. The decimation of the Black Sea Fleet has reopened exports from Odesa, but made little contribution to the ability of 2023’s counteroffensive to retake lost territory. And strikes on arms dumps behind the front lines and sabotage within Russia have reduced the flow of materiel going to the Russian army, but not to the extent that it has had to fall back. The lesson of the past 18 months is that the deep battle complements fighting close-in and along the front line, but is not a substitute for it. Striking forces across the border from Kharkiv will provide some immediate relief to Ukrainian forces and be of significant tactical benefit; in doctrinal terms, this is a ‘close battle’ that happens to straddle the border with Russia. Overall, the challenges for Ukraine in 2024 and potential answers remain the same as before this decision: resupply of equipment and ammunition, recruitment and training of personnel, and effective defences to prevent or slow down Russian ground advances. Deep strike is not a silver bullet.

The views expressed in this Commentary are the author’s, and do not represent those of RUSI or any other institution.

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