Deterrence on Trial: Russia’s Airspace Infiltrations, Hybrid Probing, and the Strategic Limits of NATO’s Collective Defense

Adediran Babajide, President/CEO
Carlsron Initiative for Peace and Human Rights (CIPEHR)

 

 

Scope: NATO and European security; Russian hybrid tactics including airspace violations, drones, and probing maneuvers; historical precedents and contemporary cases; implications for Article 5 credibility, alliance cohesion, and future deterrence strategies.

Abstract

This article examines how Russia’s hybrid tactics—including airspace incursions, drone operations, and gray-zone provocations—challenge NATO’s deterrence posture and collective defense credibility. By analyzing historical precedents, including the 2015 downing of a Russian Su-24 by Turkey, and contemporary cases across NATO’s eastern flank, the study argues that NATO’s deterrence is being tested at multiple levels. The findings highlight the alliance’s difficulty in calibrating responses to sub-threshold aggression, the ambiguity of Article 5 in hybrid contexts, and the political dilemmas of escalation management. The article concludes that NATO must clarify its red lines, invest in hybrid resilience, and adapt its collective defense framework to sustain credibility in the face of evolving Russian strategies.

 

Introduction

Since its founding in 1949, NATO has relied on the credibility of collective defense—enshrined in Article 5 of the Washington Treaty—as the foundation of deterrence. Yet in recent years, Russia has adopted hybrid strategies designed not to provoke full-scale war but to test the limits of NATO’s red lines. Airspace violations, drone incursions, missile overshoots, and probing activities in the gray zone have emerged as instruments of pressure, seeking to exploit ambiguity and alliance hesitations (Radziwinowiczówna, 2020).

The question at the heart of this article is whether NATO’s deterrence remains credible under such pressure. Can the alliance maintain cohesion and demonstrate resolve when confronted with incremental, ambiguous acts that fall below the traditional threshold of armed attack?

 

Conceptual and Theoretical Framework

Deterrence theory rests on the credibility of retaliation: adversaries are dissuaded from aggression when they believe the costs will outweigh the benefits (Schelling, 1966). Yet deterrence becomes problematic when aggression takes forms short of conventional warfare. Hybrid warfare, often referred to as “gray-zone conflict,” blurs the lines between war and peace, employing tools such as cyberattacks, disinformation, economic coercion, and limited military probes (Hoffman, 2007).

For NATO, this creates a dilemma: if every minor incursion or drone flight were treated as a trigger for Article 5, the risk of escalation to full war would be intolerable. Yet failure to respond risks signaling weakness and undermining deterrence credibility. Russia’s actions must therefore be understood as strategic probes in this gray zone.

 

Russia’s Strategy of Hybrid Probing

Russia’s strategy of probing NATO defenses is not new. During the Cold War, Soviet aircraft routinely tested NATO air defenses over the North Atlantic and northern Europe. Today, these practices continue with renewed intensity.

Airspace violations: Russian military aircraft have repeatedly entered the sovereign airspace of NATO members. In 2014, during the Ukraine crisis, Russian aircraft violated Baltic and Scandinavian airspace on multiple occasions, prompting NATO to increase its Baltic Air Policing mission (NATO, 2014).

Drone incursions: Drones are now a common instrument of hybrid probing. In 2022, a Russian-made drone crashed in Croatia after crossing Hungarian and Romanian airspace—both NATO members—raising concerns about alliance readiness (BBC, 2022).

Missile overshoots and debris landings: In December 2023, a Russian missile crossed into Polish airspace near Zamość for three minutes before returning to Ukrainian airspace (The Washington Post, 2025). Similar incidents occurred in Romania in 2023, where drone fragments and crash sites were discovered in villages along the Danube. NATO members Poland, Croatia, and Romania reported debris from drones or missiles landing on their territories throughout 2023–2024.

The Turkey incident (2015): One of the most dramatic cases occurred when Turkey shot down a Russian Su-24 fighter jet that had violated Turkish airspace near the Syrian border (BBC, 2015). This incident underscored the potential for airspace incursions to escalate dangerously. While NATO backed Turkey’s right to defend its airspace, the event revealed alliance anxieties about being dragged into direct confrontation.

Escalation in 2025: Recent months show an alarming trend. In September 2025, Poland reported a large-scale drone incursion involving between 19 and 23 drones, with some shot down and airports disrupted. Warsaw invoked NATO’s Article 4, underscoring the seriousness of the incident (Wikipedia, 2025). That same month, three Russian MiG-31 fighter jets violated Estonian airspace near Vaindloo Island for about twelve minutes, prompting Estonia to request NATO consultations under Article 4 (The Guardian, 2025). Romania also reported chasing Russian drones, with debris falling on its territory, while Latvia confirmed airspace violations (Al Jazeera, 2025).

The Black Sea and Eastern Flank: Russia has also engaged in persistent air and naval provocations in the Black Sea, near Romania and Bulgaria, challenging NATO surveillance and air policing missions. These acts serve both intelligence purposes and psychological signaling: they demonstrate Russia’s willingness to test NATO’s resolve without crossing the threshold of open war (Klein, 2019).

Taken together, these incidents demonstrate that Russia is deliberately escalating the frequency and variety of gray-zone probes. They stretch NATO’s response mechanisms while stopping short of outright war.

 

NATO’s Security Dilemma

NATO’s responses to Russian probing have been cautious but deliberate. Air policing missions, rapid deployments, and enhanced forward presence battlegroups in the Baltics and Poland demonstrate a commitment to deterrence by presence. Yet these measures also highlight the alliance’s difficulty in defining thresholds.

Threshold ambiguity: When does a missile overshoot or drone incursion constitute an armed attack? At what point does a repeated pattern of violations cross from harassment into aggression? These questions remain unresolved. NATO’s strategic ambiguity may deter escalation but also creates vulnerabilities that Russia seeks to exploit (Chivvis, 2017).

Political considerations: NATO’s deterrence credibility depends on unity among members. Yet members differ in threat perception: frontline states like Poland and the Baltic countries demand robust responses, while others worry about escalation. This divergence risks undermining alliance cohesion (Smith, 2020).

The Article 5 dilemma: Article 5 was crafted for conventional warfare. Hybrid probes, by design, remain sub-threshold. Russia’s strategy of “salami slicing” allows it to advance incrementally without triggering collective defense (Thomas, 2019). This exposes NATO’s vulnerability to gray-zone tactics.

 

Strategic Limits of Collective Defense

Russia’s actions illuminate structural challenges in NATO’s deterrence posture.

Burden-sharing tensions: The credibility of collective defense depends on equitable contributions. Yet disputes over defense spending—particularly U.S. pressure on European allies—undermine NATO’s internal solidarity (Brands & Porter, 2021).

Alliance cohesion: Disinformation campaigns and cyber operations aim not only to harass militarily but also to sow political division within NATO members. By polarizing domestic debates and eroding trust in democratic institutions, Russia indirectly weakens alliance unity (Polyakova & Boyer, 2018).

Strategic overstretch: With simultaneous challenges from Russia, terrorism, cyber threats, and China’s global rise, NATO faces the risk of strategic overstretch. Russia’s probing exploits this overstretch, forcing NATO to divert resources and attention to multiple fronts (Hamilton, 2020).

 

Policy Implications and Future Prospects

To sustain credibility, NATO must adapt. Four areas of action are particularly urgent.

1. Clarify thresholds:
   NATO must articulate what constitutes a violation requiring a collective response. This does not mean publishing a rigid checklist, but rather issuing clearer strategic guidance on how Article 5 applies to hybrid threats. Doing so would reduce ambiguity, strengthen deterrence, and minimize the risk of miscalculation. A framework could classify infractions—cyber intrusions, drone incursions, missile overshoots, manned aircraft violations—with proportional response guidelines.
2. Strengthen hybrid resilience:
   NATO needs to build defenses beyond traditional military tools. This includes enhancing cyber defense through the Cooperative Cyber Defence Centre of Excellence (CCDCOE); developing anti-drone technologies; expanding strategic communications to counter disinformation; and investing in civil defense and critical infrastructure protection. Societal resilience is as important as military readiness.
3. Bolster rapid response and escalation management:
   The Very High Readiness Joint Task Force (VJTF) and NATO Response Force (NRF) must be trained not only for conventional warfare but also for rapid deployment against hybrid threats. Escalation protocols should define how to respond to repeated airspace violations without triggering uncontrolled escalation. Enhanced air policing, supported by AWACS surveillance and drone detection systems, will be essential.
4. Ensure alliance cohesion through political dialogue:
   Diverging threat perceptions among allies require sustained consultation. NATO should reinforce the political dimension of its deterrence strategy by holding regular crisis simulations, consultations with frontline states, and transatlantic burden-sharing discussions. Greater European contributions to defense—through initiatives like PESCO and the EU-NATO partnership—could strengthen resilience and credibility.

Looking ahead, U.S. leadership will remain indispensable, but credibility cannot rest solely on Washington. European allies must assume greater responsibility, both financially and militarily, to sustain long-term resilience. Strategic autonomy, pursued within the transatlantic framework, may help balance NATO’s deterrence posture in a multipolar world.

 

Conclusion

Russia’s infiltration of NATO airspace, drone operations, and hybrid tactics represent a deliberate strategy of deterrence testing. By operating in the gray zone, Moscow seeks to expose the alliance’s vulnerabilities, exploit divisions, and challenge the credibility of Article 5.

The 2015 Turkey incident illustrates the risks of escalation inherent in airspace violations, while ongoing probes from 2023 to 2025 in Poland, Romania, Croatia, Estonia, and Latvia underscore the persistence and intensification of the threat. NATO’s response, though robust in some areas, remains constrained by political divergence, threshold ambiguity, and structural overstretch.

If NATO is to sustain deterrence credibility, it must adapt to the realities of hybrid warfare. Clarifying red lines, building resilience, bolstering rapid response, and ensuring alliance cohesion are essential steps. In a multipolar world where deterrence is constantly on trial, NATO faces a defining test: adapt or risk the erosion of collective defense.

 

References

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BBC. (2015). Turkey shoots down Russian warplane on Syria border. Retrieved from https://www.bbc.com/news/world-middle-east-34912581

BBC. (2022). Russian drone crashes in Croatia after flying over NATO states. Retrieved from https://www.bbc.com/news/world-europe-60708370

Brands, H., & Porter, P. (2021). Why NATO still matters. Foreign Affairs, 100(3), 25–35.

Chivvis, C. (2017). Understanding Russian “Hybrid Warfare” and What Can Be Done About It. RAND Corporation.

Hamilton, D. (2020). NATO 2030: A Transatlantic Agenda for the Future. Brookings Institution.

Hoffman, F. (2007). Conflict in the 21st Century: The Rise of Hybrid Wars. Potomac Institute for Policy Studies.

Klein, M. (2019). Russia’s Military Strategy and NATO’s Response. SWP Research Paper, Berlin.

NATO. (2014). NATO’s Enhanced Air Policing in the Baltic Region. NATO Official Documents.

Polyakova, A., & Boyer, S. (2018). The Future of Political Warfare: Russia, the West, and the Coming Age of Global Digital Competition. Brookings Institution.

Radziwinowiczówna, A. (2020). The Gray Zone and NATO’s Deterrence Strategy. Journal of Strategic Studies, 43(4), 551–573.

Schelling, T. (1966). Arms and Influence. Yale University Press.

Smith, J. (2020). Alliance Cohesion and NATO’s Future. Chatham House Briefing Paper.

The Guardian. (2025). Estonia requests Nato article 4 consultation after ‘unacceptable’ violation of its airspace by Russian MiG-31s. Retrieved from https://www.theguardian.com/world/live/2025/sep/19/eu-sanctions-russia-oil-ukraine-vladimir-putin-volodymyr-zelenskyy-donald-trump-france-macron-europe-live-news

The Washington Post. (2025). Russia’s violation of Poland’s airspace is the most serious in a string of cross-border incidents. Retrieved from https://www.washingtonpost.com/world/2025/09/10/russia-nato-members-borders-airspace-violations

Thomas, T. (2019). Russia’s 21st Century Hybrid Warfare. Military Review, 99(2), 34–45.

Wikipedia. (2025). 2025 Russian drone incursion into Poland. Retrieved from https://en.wikipedia.org/wiki/2025_Russian_drone_incursion_into_Poland