What Russia’s ‘red line’ actually is

Ukraine has requested permission to strike inside Russia with Western-provided weapons. In return, Vladimir Putin has warned that Moscow will consider NATO countries “at war” with Russia if restrictions on long-range munitions are relaxed to allow this.

The controversy has revived longstanding concerns over how to balance support for Ukraine against nuclear escalation risks. Yet much of the debate over Russia’s “red lines” has relied on a static framing of Russian military strategy that, paradoxically, both exaggerates and downplays Moscow’s willingness to retaliate against Ukraine and the West.

Russia’s 2022 invasion of Ukraine and the provision of Western military aid to Kyiv has been accompanied by concerns that Moscow, if pushed too far, could raise the stakes in a way that draws NATO into a direct confrontation — something that the Biden administration and key U.S. allies prudently seek to avoid. But the West has steadily deepened its involvement in the Ukraine War, including through the delivery of new types of weaponry and by redoubling its efforts to furnish Ukraine with targeting information and other military intelligence without provoking a catastrophic Russian response.

The Kremlin’s seeming inaction in response to this active Western involvement has led some observers to conclude that Russia’s red lines are little more than a psychological ploy by the Kremlin to dissuade the West from aiding Ukraine. To the extent that Moscow has actual red lines, the argument goes, they are so far removed from anything the West is now doing that there is little to worry about. Washington and London can thus safely allow Ukraine to strike inside Russia and can surge weapons shipments to Kyiv without fear of reprisal.

This cavalier approach toward escalation management, while convenient from the standpoint of Western policymakers, rests on a dangerous misunderstanding of Russian strategic thinking. It is true that Russia has tried and failed, less by concrete action and more through menacing rhetoric, to deter Western involvement in the war. But the Kremlin’s threshold for engaging in escalation is not contingent on any specific Western action. There is no precise tripwire, so to speak, that would automatically trigger a Russian attack on NATO or the use of nuclear weapons.

Rather, Moscow’s red lines are contextually determined by the battlefield situation in Ukraine. Putin has been loath to escalate because he believes, not without some justification, that Russia is winning the war at its current cadence and has nothing to gain from pushing it into a new, more dangerous phase.

Putin has demonstrated since Ukraine’s failed 2023 counteroffensive that he does not want to disrupt what he sees as a favorable military status quo with escalatory moves that would weaken Russia’s position. Russia’s strategy appears to be premised on the assumption that sharply escalating the conflict may provoke direct Western intervention in Ukraine, which carries with it the specter of a wider war that both Moscow and Washington rightly regard as catastrophic in its implications.

On the political front, the Kremlin has worked to assure key international partners, including China, Brazil and India, that it is doing all it can to swiftly end the war with a negotiated conclusion. Opening a new rung on the escalation ladder would make void this longstanding position and cost Moscow support from countries that it can ill afford to alienate, as it works to mitigate the effects of international sanctions.

Instead, the Kremlin seeks to stay the course in what it sees as its successful attrition strategy, leveraging its massive advantages in manpower and armaments to slowly grind down Ukrainian forces along the lines of contact. The reverse is also true: Moscow’s real “red line” is not a specific action but rather a situation in which it concludes it cannot win the war without embarking on a major escalation. That conclusion, if it is reached, would push Putin toward options that were previously dismissed as too risky or counterproductive.

Crucially, this perception does not have to meet the standard of Russian forces in Ukraine finding themselves on the verge of battlefield defeat. It is enough for the Kremlin to conclude that Russia is on a trajectory of defeat for it to start exploring high-risk options, including direct conventional strikes on targets in NATO territory and even high-level consideration of what a nuclear option could look like.

Allowing Ukraine to hit targets inside Russia is presented by proponents as an attractive option precisely because it does not seem to meet the criteria outlined above, and thus would not run afoul of Russia’s red lines. That is, it cannot shift the underlying military calculus in a way that significantly increases Ukraine’s chances of winning.

The problem, however, lies in Russia’s perception — starkly presented by Putin’s recent warning to NATO — that the West will continue to gradually deepen its involvement in Ukraine until, potentially through troop deployments or direct Western interception of Russian missiles, it does eventually manage to prevent Russia from achieving something that the Kremlin considers a victory.

The danger is that Putin may feel compelled to restore deterrence against the West before that happens, setting the stage for a direct clash neither side wants, but one that is increasingly being rendered inevitable by this war’s escalating trajectory.

The way to escape this cycle of escalation is not, as has been suggested, to furnish Ukraine with new weapons and capabilities in the misplaced hope of giving Kyiv the upper hand and therefore a path to securing peace on advantageous terms. Nor is it to sever Western aid altogether. NATO’s present levels of military and political support, coupled with the international sanctions regime on Russia, already give it considerable influence in paving the way for negotiations on the best possible terms for the West and Ukraine.

The time has come for Western leaders, in close consultations with Kyiv, to cash in that leverage. This will require vision and initiative in abundance, but the costs of inaction — both to Ukraine’s deteriorating battlefield position and in growing risks of catastrophic escalation — are much greater.

Mark Episkopos is a research fellow in the Eurasia program at the Quincy Institute for Responsible Statecraft.