Dr Giles David Arceneaux
Throughout the war in Ukraine, the United States has steadily increased the scale and scope of its support for Ukraine. Despite broadening material support over time, however, the United States has imposed one persistent restriction on Ukraine’s use of US-supplied weapons: a prohibition against using those weapons on Russian territory.
Now, more than two years after Russia’s full-scale invasion of Ukraine, that policy is changing. For the first time, US President Joe Biden has authorized Ukraine to use US weapons to attack targets within Russian borders.
Supporters of the shift in US policy have praised the decision, noting that Russia’s threats to escalate in retaliation have proved empty. In contrast, others have expressed concern that enabling attacks on Russian territory could encourage Russia to significantly escalate the conflict, including considerations of nuclear use.
Both schools of thought entail elements of truth, but both perspectives are also incomplete. Countering Russian aggression requires a willingness to accept significant risk, while also understanding that a variety of intentional and unintentional pathways to significant escalation exist and must be managed. In practice, US policymakers must strike a balance between these two realities.
The US goal of enabling the liberation of Ukrainian territory is inherently in tension with the Biden administration’s concerns about crisis escalation. This tension, however, can be mitigated by resisting calls to abruptly expand Western involvement in Ukraine. By continuing to incrementally expand its support over time, the United States can better navigate the difficult path of supporting Ukraine while managing the very real risks of escalation.
Cause for Change in US Policy
The decision to allow Ukraine to target Russian territory with US weapons comes in response to recent Russian success in seizing territory in Ukraine’s Kharkiv Oblast. Russia’s gains were enabled by Ukraine’s inability to attack Russian forces while they staged for the May 2024 offensive. Despite Russian units openly amassing only twenty miles from Kharkiv, Ukraine was unable to attack those forces.
The change in US policy follows similar statements from European partners. UK Foreign Secretary David Cameron indicated in early-May 2024 that the United Kingdom would support Ukraine’s use of British-supplied weapons against Russian territory. France and Germany subsequently expressed similar support, and NATO Secretary General Jens Stoltenberg openly called on NATO countries to “lift restrictions” on how Ukraine uses weapons to defend itself.
In response to these statements, Russian President Vladimir Putin warned of “serious consequences” for NATO countries and accused the West of wanting a “global conflict.” And, as he has done throughout the war in Ukraine, Putin directly referenced the nuclear dangers of conflict by emphasizing Russia’s nuclear capabilities.
Importantly, these escalating tensions between Russia and the West over Ukraine’s ability to target Russian territory provide a new angle on a debate that has endured for the duration the war in Ukraine: the likelihood of Russia acting on its nuclear threats.
Evaluating Russian Threats
Despite persistent nuclear saber rattling by Russia, the war in Ukraine has not gone nuclear. As a result, skeptical observers—referred to here as escalation optimists—have determined that Russian nuclear threats are merely rhetorical bluffs.
Two factors seemingly lend support to the perspective that Russian nuclear threats are empty.
First, the West has provided extensive and expanding support to Ukraine without provoking a nuclear response. Over time, the United States has slowly but deliberately defied Russian threats by providing a wide array of capabilities. In each instance, Russia failed to follow through on its nuclear threats.
Second, Russian threats to initiate a nuclear exchange with other nuclear-armed countries over arms provisions inherently lack credibility. Such threats are dubious even under conditions of existential risk, and those threats become less believable as the stakes of conflict are reduced. Global isolation and political costs would also likely follow Russian nuclear use, adding additional penalties that further challenge the credibility of Russia’s nuclear threats.
These two observations combine to reveal a simple but important point: Russia’s nuclear threats can—at least under certain circumstances—be circumvented.
The United States’ slow and methodical approach to increasing its support for Ukraine has thus far safely avoided major escalation triggers. No individual transgression by the United States has been sufficiently impactful to justify a major Russian response, even though the sum of the actions produces an outcome across the threshold of what Russia initially deemed acceptable. These salami tactics present a challenge for Russian retaliation that seemingly reduce the likelihood of escalation.
Appreciating Nuclear Risks
The ability to work around Russia’s nuclear threats thus far, however, should not lead to a dismissal of such threats as bluffs. Russian leaders are certainly aware of the credibility problems that come with nuclear threats. Russia’s goal is not to threaten that nuclear escalation will necessarily follow a particular action, but rather to generate uncertainty and create conditions that increase the likelihood of a crisis spiraling out of control.
The evolution of Russian nuclear threats over time reveals a consistent effort to make nuclear use more plausible. Actions such as the Russia-Belarus nuclear sharing agreement, exercises involving tactical nuclear weapons, an apparent broadening of nuclear first-use conditions, and the possibility of reduced decision time for nuclear use demonstrate a concerted effort to increase the likelihood of miscalculation resulting in nuclear escalation. The development of such pathways to nuclear escalation generates real dangers that cannot be dismissed outright.
However low the risk of nuclear escalation might appear, it is not zero. Given the risks of a nuclear exchange, policymakers must remain careful in their estimations of Russian responses and avoid reflexive responses that do not seriously evaluate the likelihood of initiating an escalatory spiral.
Managing Escalation
Given the potentially catastrophic consequences of nuclear escalation, a second analytical community of escalation pessimists argues that the United States should limit its involvement in Ukraine.
Two items motivate the argument for moderating US support.
First, the asymmetry of interests between Russia and the United States in Ukraine favors Russia. In July 2021, Putin authored an essay that denied Ukraine’s sovereign status revealed Putin’s commitment to imperialist ambitions. The war in Ukraine has since become a defining feature of Putin’s rule, and the survival of Putin’s regime may be connected to the outcome of the war. Unlike Ukraine’s supporters in the West, Putin’s future may rely on victory in Ukraine, and he may be willing to go to extreme lengths to guarantee his regime’s survival.
Second, those who are quick to dismiss Russian nuclear threats understate the varieties of pathways that might result in nuclear use. Whereas the debate often focuses on whether Putin would deliberately choose to use nuclear weapons, the potential for inadvertent escalation looms large. As Russia alters its policy to signal greater resolve in its nuclear threats, the United States must contend with the very real possibility for accidental or unauthorized use to occur, even if Western actors merely approach what appear to be Russia’s red lines.
Competitive Risk-Taking
US National Security Adviser Jake Sullivan has noted that escalation concerns have substantially shaped the Biden administration’s willingness to challenge Russia in Ukraine. Biden has remained deeply cautious in his dealings with Russia, and the limited expansion of Ukrainian targeting permissions suggests he remains concerned about the prospect of unwanted escalation.
Prudence is warranted in the campaign to counter Russian aggression in Ukraine. But, if the West’s goal is to support the liberation of Ukraine from Russian occupation without starring World War III, US policymakers must be willing to accept risk against a motivated adversary.
When competing under the nuclear shadow, threats to purposefully use nuclear weapons often lack credibility. As a result, states typically engage in competitive risk-taking measures that increase the likelihood of a crisis spiraling out of hand to signal resolve. In effect, to deter an opponent from escalating and compel that opponent to change their behavior, states must create conditions that increase the likelihood of uncontrollable escalation.
The dangers of competitive risk-taking are real, but also necessary to achieve coercive success in a dispute involving nuclear weapons. Although the concerns of nuclear escalation are more severe than many observers admit, Western partners must nevertheless be willing to accept notable risks if their ultimate objective is to enable a Ukrainian victory against Russia.
Walking the Nuclear Threshold
Allowing Ukraine to expand its targeting into limited portions of Russian territory increases the likelihood of escalation, but also represents a limited action that complicates Russian responses. Although Russian statements are attempting to connect the West’s new targeting permissions to nuclear dangers, the West has now placed the onus of accepting serious escalatory risks on Russia.
The United States should not, however, recklessly reject all Russian threats as bluffs and create conditions that compel Russia to rapidly escalate. For example, the proposal for a no-fly zone early in the war would have involved NATO forces directly fighting Russian forces and forced Russia to consider extreme steps to offset potentially rapid conventional losses. But, as more than two years of war in Ukraine have shown, more limited options exist that can help deny a Russian victory and reduce the likelihood of nuclear escalation.
Russia’s nuclear threats must induce caution in the war in Ukraine. But, if the West is to help Ukraine prevail, accepting risk will be a necessary component of future policy decisions. Charting a policy course that attempts to account for both imperatives will remain a central challenge for US policymakers throughout the war in Ukraine, and calculated policymaking will need to resist the impulse to rapidly deviate from the established but perilous path forward.
Giles David Arceneaux is the Rossetti Senior Research Fellow for Future Conflict at the United States Air Force Academy’s Institute for Future Conflict and an assistant professor of political science at the University of Colorado, Colorado Springs. The views expressed in this piece are those of the author and do not reflect the official policy or position of the US Air Force, the US Department of Defense, or the US government.