The NATO Tripwire is Not an Effective Deterrent

The Russian invasion of Ukraine has taught the world important lessons about European security. Chief among these lessons is that the ability of the United States to deter conflict is not as absolute as once believed. Though Ukraine is not an American treaty ally, it is a security partner and a democratic state. Russia’s aggression against Ukraine is both an effort to resist expanding American influence in Europe and an attempt to test Western resolve in the face of a challenge to the rules-based international order. The North Atlantic Treaty Organization’s (NATO) current deterrence strategy in the Baltics states of Latvia, Lithuania, and Estonia involves a tripwire force, a cheap strategy that relies on an intentionally small deployment whose deaths are meant to assure larger confrontation. The logic of the tripwire holds that Russia is so fearful of an all-out conflict with NATO that it will not aggress against the tripwire because doing so would require those NATO countries to escalate the conflict. This strategy is predicated on assumptions about the cohesion of NATO as a partnership and the strength of NATO’s Article V guarantee — that a war against one is a war against all. As the invasion of Ukraine has demonstrated, however, these assumptions lack the weight they once held. Russia no longer believes that NATO is willing to make the costs of aggression outweigh the benefits. This reality calls for a serious look at the U.S. current deterrence strategy in Europe and a revitalization of NATO defenses in the Baltics.

NATO’s Baltic tripwire is an inadequate defensive force. NATO’s Enhanced Forward Presence is composed of roughly 5,000 troops meant to defend against the forces of Russia’s Western Military District, which a 2021 report from the think tank CNA called Russia’s “most robust, most numerous, and most capable fighting forces.” [1][2] This disparity in force strength has led the Baltic leaders to request a significant increase in NATO deployments and defensive capabilities. [3] Indeed, the tripwire force would likely be overrun quickly by the initial Russian assault. A 2016 report from the RAND Corporation found across several wargames that the longest it would conceivably take Russian forces to reach the “Estonian and/or Latvian capitals of Tallinn and Riga, respectively, is 60 hours.” [4] David Shlapak and Michael Johnson, the authors of the report, further argued that the size of NATO forces in the region was so insufficient that, in their simulation, “NATO’s infantry found themselves unable even to retreat successfully and were destroyed in place.” [5] University of Maryland Professor Thomas Schelling, a proponent of the tripwire force, argued in his 1966 book, Arms and Influence,that if a numerically inferior Allied force in West Berlin was to “die heroically” in the event of a Soviet invasion, the deaths would be a casus belli, inviting a swift and overwhelming Allied response. [6] Supporters of the Baltic tripwire strategy use an analogous argument. They assume that Russia fears a direct confrontation with the United States, and so it will not invade the Baltics in the first place. However, if Russia believes it can achieve a swift fait accompli in the Baltics, Russian President Vladimir Putin may calculate that NATO will not retaliate with all-out war because retaking the Baltics would be so costly. Thus, a Russian assault on the Baltics could result in one of several outcomes: a bloody, risky NATO counteroffensive to retake the Baltics, nuclear war, some form of grey zone warfare or sanctions that represent a failure on NATO’s part to act meaningfully, or NATO failing to act at all. All of these outcomes are highly dangerous.

Figure 1: Map of the Suwalki Gap and the Surrounding Territories [7]

A NATO invasion to reclaim the Baltics would be a logistical nightmare. Except for the 65-kilometer long Suwalki Gap between Kaliningrad Oblast and Belarus, the Baltics are surrounded by the Baltic Sea to the west, the Russian mainland to the northeast, the Russian exclave of Kaliningrad to the southwest, and Russia’s ally Belarus to the southeast. [7] Russia could easily mine Baltic ports as they have done in Ukraine, making it impractical to attempt an amphibious invasion from the sea. [8] Meanwhile, Kaliningrad is the heavily fortified home to a host of Iskander missiles which can hit targets in the Baltics themselves, the Baltic Sea, or Poland to slow a NATO counterattack. Moreover, Lithuanian officials have claimed that Russia is storing nuclear missiles in Kaliningrad, which – if true – would put NATO in an even more difficult position for an assault by land lest they force Russian president Vladimir Putin into a ‘use it or lose it’ scenario that results in a nuclear launch. [9] The current posture leaves NATO, as the RAND Corporation report concludes, “with a limited number of options, all bad.” [10] A costly, bloody war to retake the Baltics would risk conventional and nuclear escalation and be cataclysmic for the civilian population of the Baltics. Tripwire force proponents might argue that the addition of Finland and Sweden to NATO will alter the balance in the region, as Allied forces will be able to deploy more quickly from the north, as well as the south in Poland. However, Russian officials have already threatened to fortify Kaliningrad Oblast with hypersonic and nuclear weapons in the event of Swedish and Finnish accession to NATO. [11] If Russia were to follow through with these threats, such weaponry would only increase the escalation risks involved a campaign to retake the Baltics.

Atop the shortcomings of the tripwire strategy at a logistical level, the war in Ukraine should create serious doubts about NATO’s will to pursue a long, difficult campaign to retake the Baltics. While the war in Ukraine has demonstrated that the Russian military is far weaker and less effective than many had initially predicted, it has also demonstrated the tenuousness of the Western alliance. Whether or not NATO can remain politically cohesive while churning out armaments in the event of a direct, protracted conflict with Russia is a grave concern. The beleaguered Ukrainian forces have fought valiantly but are now running out of weapons, and as of August 18, the United States has delivered less than a quarter of what it has committed to Ukraine. [12] American stockpiles of some military systems, ammunition, and equipment are now “depleted” and “the Pentagon has been slow to replenish its arsenal.” [13] Moreover, French and German leaders have publicly undermined European Union sanctions on shipments of goods from Russia to Kaliningrad through Lithuania. [14] Russia may observe the fissures appearing in both Western resolve and in the military industrial base and seek to exploit those weaknesses in future acts of aggression. Moreover, President Joe Biden’s decision to pull American national guardsmen out of Ukraine on the eve of the invasion may contribute to a Russian perception that it can easily rout the tripwire force and expect little direct military retaliation from NATO. [15] Putin may assume that President Biden will be unwilling to risk New York for Riga, Tallinn, or Vilnius.

Another risk of the tripwire force is that an insufficient amount of blood will be spilled in Russia’s initial invasion to provoke a military response from NATO. Increasing populism and isolationism in Western democracies leaves a not-insignificant chance that some NATO countries may opt for either no response at all, or a response so weak – like sanctions or limited cyber-attacks – that the alliance’s Article V guarantee would effectively lose all credibility either way. Such an outcome would mean nothing short of the collapse of the international rules-based system. Given that the United States is NATO’s largest security guarantor, a failure to invoke Article V in the face of a Russian invasion – even if invocation is blocked by a country other than the United States – will undermine the legitimacy of international American security guarantees. A perception in the international community that the United States is unwilling to defend its treaty allies would invite a cascade of aggression from American adversaries and a dramatic increase in the appeal of nuclear proliferation among American allies. The probability of such an outcome, though low, is nonzero, and it would be so disastrous that despite its relatively low probability, strategists would be wise to hedge against it. Even if the security guarantee does withstand the domestic pressure it currently faces in powerful Western states, a stalemate conflict in the Baltics could also signal weakness to American allies, increasing the chances that they proliferate to defend themselves. Proponents of retrenchment as grand strategy often argue that concerns over global ripple effects from changes to security commitments are exaggerated. For instance, University of Notre Dame Professor Joseph Parent and Wellesley College Professor Paul MacDonald argued in a 2011 Foreign Affairs article that the United States is currently an overstretched superpower that runs the risk of trying to deal with too many concurrent crises in too many places, and that this represents a greater risk to stability than retrenchment. [16] They have the correct diagnosis but the wrong prescription. Current overstretch requires not a reduction in American commitments, but an enlargement of the resources and manpower the United States uses to fulfil them. Indeed, retrenchment in the face of Russian aggression in Ukraine is an admission that Putin’s assumption about Western lack of resolve is correct.

What remains most concerning is that the prospect of a protracted conflict in the Baltics risks emboldening adversaries to initiate conflicts in other hotspots. If they believe that Western attention is focused elsewhere, opportunistic adversaries like Iran, North Korea, or China could seize the moment to pursue their respective military aims. This creates what can best be described as a multiplier effect for geostrategic crises; the U.S. inability to deter aggression against any one of its of its allies may signal its inability to deter aggression against all of its allies. Adversarial conflict initiation based on the perception that the United States is bogged down in an Eastern European quagmire would test the ability of an overstretched hegemon to handle multiple conflicts at once. A failure to manage such circumstances would likely result in significant geopolitical instability that risks widespread allied proliferation, erratic military actions by partners and foes alike, and the collapse of the rules-based international order.

Consequently, NATO should pursue a stauncher forward presence in the Baltics. Such a presence must include counterforce measures that specifically target weaknesses in the current defensive posture, namely minesweeping vessels, heavy armor divisions, greater airpower, and improved fortification and infrastructural development in the Suwalki Gap. In addition to counterforce measures aimed to deprive Russia of potential advantages, the forward presence must also include several brigades of heavy armored units that are better able to spar with Russian armored forces than the current light brigade deployment. With a larger force presence in the Baltics, NATO could worry less about a Russian fait accompli or wavering domestic support for NATO because the probability of Russian aggression will be significantly diminished. Critics of a robust defensive presence have claimed that any military buildup will aggravate Putin and increase the risk of conflict. [17] This claim is not baseless; however, Putin has already committed the first act of aggression by invading Ukraine. Putin’s gambit to test the resolve of NATO, must be met with staunch resilience and a clear message that NATO is capable and willing to defend itself. A reinforced defensive posture does not require a massive forward invasion force but rather prudent measures that make invasion unappealing to Russian strategists and deny Russia the ability to achieve rapid victory. Bolstering the defensive posture is not a substitute for diplomacy with Russia where such diplomacy can be sustained, but rather a reaction to the facts on the ground, which no longer support the existing strategy. A stronger defensive posture would reassure our allies across the globe that we remain committed to their defense, and signal to Russia the risks associated with directly attacking NATO countries.


[1] “NATO Shows Little Appetite for Thousands More Troops in Baltics,” Lithuanian National Radio and Television, 16 June 2022,

[2] Konrad Muzyka, Russian Forces in the Western Military District, IOP-2020-U-028759-1Rev (Arlington, VA: CNA, June 2021), 4,

[3] “NATO Shows Little Appetite for Thousands More Troops in Baltics,” Lithuanian National Radio and Television, 16 June 2022,

[4] David A. Shlapak and Michael Johnson, Reinforcing Deterrence on NATO’s Eastern Flank: Wargaming the Defense of the Baltics, RR-1253-A (Santa Monica, CA: RAND, 2016), 1,

[5] Shlapak and Johnson, Reinforcing Deterrence, 6.

[6] Thomas C. Schelling, Arms and Influence (New Haven, CT: Yale University Press, 1966), 22.

[7] Max Bearak, “This Tiny Stretch of Countryside is All That Separates Baltic States from Russian Envelopment,” The Washington Post, 20 June 2016,

[8] Julian Borger, “Russian Navy Ordered to Lay Mines At Ukraine’s Black Sea Ports, Says US,” The Guardian, 23 June 2022,

[9] “Russia Already Has Nuclear Weapons in the Baltic Region, Says Lithuania,” U.S. News & World Report, 14 April 2022,

[10] Shlapak and Johnson, Reinforcing Deterrence, 1.

[11] Guy Faulconbridge, “Russia Warns of Nuclear, Hypersonic Deployment if Sweden and Finland Join NATO,” 14 April 2022,

[12] “Ukraine Support Tracker,” Kiel Institute for the World Economy, 18 August 2022, Accessed September 9, 2022,

[13] Gordon Lubold, et al., “Ukraine War Is Depleting U.S. Ammunition Stockpiles, Sparking Pentagon Concern,” Wall Street Journal, 29 August 2022,

[14] Dalibor Rohac, “Biden Must Stop Germany and France From Wavering On Ukraine,” New York Post, 12 July 2022,

[15] Jim Garamone, “More U.S. Troops Deploying to Europe, Guard Leaving Ukraine,” National Guard, 15 February 2022,

[16] Joseph M. Parent and Paul K. MacDonald, “The Wisdom of Retrenchment: America Must Cut Back to Move Forward,” November/December 2011,

[17] Andrew Radin, “How NATO Could Accidentally Trigger a War with Russia,” The RAND Blog, 13 November 2017,

Image:  “Kamala Harris met with leaders of the Baltic states during MSC 2022,” by Office of the Vice President of the United States, retrieved from, permission is granted to copy, distribute and/or modify this document as this file is a work of an employee of the Executive Office of the President of the United States, taken or made as part of that person’s official duties. As a work of the U.S. federal government, it is in the public domain.

Related Posts