Abstract: In response to growing Russian airspace violations against NATO member states, this paper looks at the role of NATO Article 4 as more than a symbolic mechanism of consultation. Through the lens of Poland, Romania, and the Baltic States, it argues that Article 4’s effectiveness depends on ensuring that political signaling can be transformed into actual deterrence measures. Historical precedents, such as Türkiye’s invocations during the Syrian conflict, and Eastern Europe’s invocation after Crimea was illegally annexed, demonstrate the potential to unify allies but also that actions afterwards are not always reliable. This paper shows that inconsistent rules of engagement and underdeveloped air defense coordination have weakened NATO’s credibility, and it recommends standardizing ROE across the alliance, expanding Integrated Air and Missile Defense deployments, and tying Article 4 consultations to operational outcomes. With these changes, NATO will be able to deter minor incidents, all while avoiding unintended escalation. Ultimately, Article 4 must evolve from a reassurance clause into a proactive instrument of strategic deterrence and alliance cohesion.
Keywords: NATO Article 4, airspace violation, deterrence, alliance, NATO response
Meta Description: This paper looks at NATO’s Article 4 through Polish, Romanian, and Baltic case studies to suggest new policy due to Russian airspace violations.
Introduction
Ever since Russia’s illegal annexation of Crimea in 2014, NATO has been put under increasing pressure in numerous different forms, testing the alliance’s cohesion and readiness. Among some of the most recent and troubling provocations are violations of NATO member states’ airspace, ranging from drones to cruise missiles, and even manned aircraft. Such incidents are not only a breach of sovereignty as we know it, but also a direct challenge to NATO’s credibility as a source of power on the world stage. This has been drawn increasingly into the light, when on September 10th, 2025, Poland was forced to shoot down multiple Russian drones that crossed into its airspace, and the Polish government invoked NATO’s Article 4 requiring consultation among the member states. This was then followed by an incursion of three Russian jets over Estonian airspace, causing them to invoke Article 4 as well. These episodes have underscored the continuing relevance of NATO’s founding treaty at one of the most trying times since the group’s creation in 1949. The response to these airspace violations raises two key questions. First, how have NATO members historically responded to breaches of their sovereign airspace since 2014? And secondly, what lessons can be drawn from past invocations of Article 4 that might guide the way decision makers think about these sorts of events? To address these questions, this paper will examine not only the incidents themselves but what measures already exist to deal with them, and how they have been managed in the past. In the past, Article 4 has been used to signal that a situation needs to be taken more seriously, however, it does have severe limitations and with increasing Russian provocations NATO faces a need for more concrete solutions. Through the case studies of Poland, Romania, and the Baltic states, and by situating them within NATO’s institutional and historical context, this analysis demonstrates that Article 4 should evolve from a symbolic reassurance measure into a proactive instrument of alliance strategy.
Functionality of Article 4
Understanding the situation NATO now finds itself in, requires at least some level an understanding of the mechanisms that dictate how NATO responds to conflict. For this purpose, the North Atlantic Treaty has two articles that deal with external threats to the alliance, Article 4 and Article 5.[1] Article 5 states that an armed attack against one member in a conventional setting is an attack against all and is the most commonly known article. However, less often discussed in the mainstream media, but especially relevant today, is Article 4, which states that any member may request consultations when it feels its territorial integrity, political independence, or security is threatened.[2] Unlike Article 5, it doesn’t say that any of the member states have to go to war, but rather that, “The Parties will consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the Parties is threatened.”[3] Article 4 is not often used, however in the past it has generally been used in more serious situations when a NATO member state is worried about the potential for armed conflict.
Previous Uses of Article 4
Türkiye has used it most often, requesting consultations during the Iraq War in 2003, the Syrian Civil War in 2012, and the rise of ISIS in 2015.[4] In those cases, Türkiye used it not to trigger military intervention but instead to rally political support, secure reassurance measures, and emphasize Türkiye’s vulnerability as a frontline state. Poland and the Baltic states also invoked Article 4 in 2014, immediately after Russia’s annexation of Crimea. They did this to express their concern that Moscow’s aggression might extend beyond Ukraine’s borders with the hopes of displaying to the world, and Russia, a united NATO front. For smaller states, the value of Article 4 lies in elevating their security concerns onto NATO’s agenda, giving all states equal priority in the case of security guarantees. Yet the non-binding nature of Article 4 also creates limitations. When Article 4 was used in the past, often what comes out are symbolic measures, rather than sustained policy change. Türkiye’s 2012 invocation after Syrian shelling led to the deployment of Patriot missile batteries, but only on a temporary basis.[5] Similarly, when Poland, Lithuania, Latvia, and Estonia called for Article 4 in 2014, new exercises were planned and there were promises for increased air policing, but it was not what the 4 countries had hoped for in the sense of a long-term commitment. Airspace violations sharpen this tension. They are serious violations of a nation’s sovereignty, however technically they are not considered “armed attacks,” as specified in Article 5.[6] If consultations are treated as routine and cost-free, they risk becoming hollow rituals and allow for potential escalations later. But if they are ignored or dismissed, smaller states may conclude that the alliance cannot be trusted to act in their defense when that escalation occurs. This is where the need for Article 4 comes into play. Nato needs a measure that is meaningful, flexible, and capable of reassuring members while not obligating NATO to responses it cannot sustain. Clearly defining when and how this measure should be implemented will have increasing priority with the rising tempo of Russian airspace violations in Eastern Europe.
Incursions into NATO airspace
Poland has been subject to multiple incidents of Russian airspace violations during the Russian invasion of Ukraine, with the first event occurring on December 16, 2022, when a Russian missile hit northern Poland after disappearing temporarily for NATO’s radar.[7] A year later, a similar event happened when a missile entered Polish airspace for three minutes, and afterwards the Russian chargé d’affaires was summoned in protest.[8] Then in March 2024, another Russian cruise missile aimed at targets in Ukraine violated Polish airspace near the village of Overdo, and Polish and allied aircraft were activated.[9] In 2025, these incidents became more frequent, and another violation was documented on February 11, 2025, when a Russian Su-24 aircraft violated Polish airspace near Gdansk Bay, attributed by Russia to a navigational malfunction.[10] There was then a Russian helicopter that violated the airspace over Polish waters on April 25th,[11] a Russian drone on August 20th,[12] two more Russian drones on September 4th, another drone on September 8th(although this has not been officially confirmed as Russian),[13] and most recently the drones that violated Polish airspace on the night of September 9th, forcing Poland to shoot a couple down.[14]
Romania has also experienced multiple Russian airspace violations during the same period, many involving drones or drone fragments, sometimes brief incursions and in other cases detection with scrambling of Romanian jets. The first of such incidents occurred early into the war on March 14th, 2022, when a Russian Orlan-10 drone crashed in north-eastern Romania.[15] This was followed by a year and a half period where there were no further incidents, and then a sharp escalation when on 4 different occasions from September-December 2023 Romania’s airspace was again violated by Russian drones. These incidents, on September 9th[16], 13th[17], and 30th[18], along with the violation on December 14th[19], reveal both vulnerability and constraints in Romania’s defense posture, particularly along its border with Ukraine. On July 26th 2024, Romania again found debris of a Russian drone within its territory after the Ukrainian army reported the incursions to Romanian authorities.[20] Again around September, there was another flurry of violations on September 8th[21] and 27th[22], and October 17th and 19th of 2024[23], with both September cases having direct confirmation of Russian drones, whereas in the October occasions NATO aircraft were scrambled but were unable to identify what violated Romania’s airspace. More recently, on September 13, 2025, a Russian drone was detected in Romanian airspace, and two F-16s were scrambled, tracking it until it left their airspace.[24]
The Baltic States, especially Estonia, are the last NATO states to have experienced airspace violations because of Russian aggression. The September 19, 2025, event marked a clear escalation and departure from past incidents. In this case, three Russian MiG-31 fighter jets entered Estonian airspace with no flight plans, transponders, or communication with Estonian air traffic control. They then remained over Estonian territory for approximately twelve minutes before being intercepted by Italian F-35s deployed under the NATO Baltic Air Policing mission.[25] Estonia then characterized the incursion as “unprecedentedly brazen,” and proceeded to invoke Article 4 in response.[26]
Suggestions for Future Policy
Despite these great successes in past uses of Article 4, NATO’s credibility is increasingly being tested by Russian violations of member states’ airspace. While the consultations have been great for signaling and political reasons, the alliance must develop a set of practical policy options that go beyond dialogue. NATO needs to do something to strengthen deterrence, improve coordination, and make sure that airspace violations are not normalized as acceptable gray-zone provocations. One of the biggest problems exposed by recent incidents in Poland, Romania, and Estonia is the ambiguity of response, because currently NATO members apply different standards. Romania, for example, scrambled F-16s in September 2025 but refrained from firing on a Russian drone due to concerns about collateral damage despite their authorization to do so. In contrast, Poland shot down multiple drones when their air space was violated, whereas Estonia intercepted the Russian planes and escorted them out. A clear, alliance-wide set of rules of engagement (ROE) would reduce ambiguity and strengthen deterrence. This could look like escorting any manned aircraft out of member territory, and shooting down anything unmanned, this way it is clear to any adversary the consequences of their actions. This standardized ROE would reduce adversary opportunities to exploit hesitation among frontline states, because while NATO’s air policing missions provide visible reassurance, now they are insufficient against persistent drone and missile incursions. Another solution could be to expand Integrated Air and Missile Defense (IAMD) deployments to frontline states. In deploying additional Patriot, NASAMS, or SAMP/T systems in Poland, Romania, and the Baltics, it would not only serve political goals of displaying a united front, but also for easier tracking of these incidents and make responding to them even more of a viable option. In this case, there is even precedent for a response like this as when Türkiye invoked Article 4 in late 2012, Patriot missile systems were deployed within weeks. A similar model could be adopted today, with rotating batteries covering vulnerable air corridors in Eastern Europe and providing reassurance to NATO’s eastern flank states. However, if NATO does want to retain the ambiguity aspect of Article 4, without a guaranteed commitment of resources, what they also could do is create a process where Article 4 triggers numerous potential responses which could include, reinforcement of air policing, rotation of missile defense units, or deployment of new assets. Creating a process like this would make sure that consultations are not merely symbolic but tied to concrete outcomes. A change like this would also not require amendments to the existing treaty, simply agreement among the member states to implement new policy. Creating this bridge between political vs. operational responses would create a situation that shows to the world that provocative actions have consequences, strengthening NATO.
Conclusion
Finally, NATO must make sure that its responses avoid any unintended escalation. While Russia’s airspace violations do pose serious threats, Russia has calculated these actions very closely as to not invoke Article 5. Responding with disproportionate force could provide Russia with the sort of justification needed for counter-escalation, or at the very least with propaganda to use at home or to rally support abroad. That being set, overly cautious responses invite further testing and an emboldened Russia who might try something that will trigger Article 5. The trick then is establishing a balance with clear signaling, consistent enforcement of ROE, and proportional defensive actions. Within this balance, shooting down drones, intercepting and shadowing manned aircraft, and reinforcing air defenses are all reasonable actions unlikely to cause any major escalation. What NATO must avoid is paralysis (which undermines credibility) or overreaction (which risks war). So far NATO has been choosing to risk their credibility, as war is clearly the worst of the 2 options, and to maintain the balance, NATO needs close coordination and political unity. These recommendations are far from perfect, but they represent reasonable and actionable steps NATO could take if it wanted to transform Article 4 from a consultation mechanism into a tool of deterrence. If they can clarify rules of engagement, strengthen air defenses, institutionalize Article 4 responses, and carefully balance deterrence with escalation management, NATO will be able to ensure that airspace violations do not become routine.
References
[1] NATO, “The North Atlantic Treaty,” April 4, 1949, https://www.nato.int/cps/en/natohq/official_texts_17120.htm
[2] NATO, “The North Atlantic Treaty,” April 4, 1949, https://www.nato.int/cps/en/natohq/official_texts_17120.htm
[3] NATO, “The North Atlantic Treaty,” April 4, 1949, https://www.nato.int/cps/en/natohq/official_texts_17120.htm.
[4] NATO, “Collective Defence—Article 5,” last updated November 15, 2019, https://www.nato.int/cps/en/natohq/topics_49187.htm
[5] NATO, “NATO Deploys Patriots to Turkey,” December 4, 2012, https://www.nato.int/cps/en/natohq/news_92861.htm
[6] NATO, “The North Atlantic Treaty,” April 4, 1949, https://www.nato.int/cps/en/natohq/official_texts_17120.htm.
[7] Wall Street Journal, “Russian Cruise Missile That Struck Poland Exposes NATO’s Air Defenses,” December 16, 2022, https://www.wsj.com/world/russian-cruise-missile-that-struck-poland-exposes-natos-air-defenses-3312d456.
[8] Reuters, “Unidentified Object Entered Poland from Direction of Ukraine, Says Polish Army,” December 29, 2023, https://www.reuters.com/world/europe/unidentified-object-entered-poland-direction-ukraine-says-polish-army-2023-12-29/.
[9] CNN, “Poland Activates Aircraft after Russian Attacks on Lviv,” CNN, March 24, 2024, https://www.cnn.com/2024/03/24/europe/poland-activates-aircraft-russia-attacks-lviv-intl/index.html
[10] Reuters, “Russian Military Jet Violates Polish Airspace after Navigation Failure,” February 11, 2025, https://www.reuters.com/world/europe/russian-military-jet-violates-polish-airspace-after-navigation-failure-poland-2025-02-11/
[11] Pravda (Ukraine), “Russian Helicopter Violates Polish Airspace,” April 26, 2025, https://www.pravda.com.ua/eng/news/2025/04/26/7509286/.
[12] Reuters, “Russian Drone Fell in Eastern Poland, Warsaw Says,” August 20, 2025, https://www.reuters.com/world/russian-drone-fell-eastern-poland-warsaw-says-2025-08-20/.
[13] Reuters, “Poland Finds Debris from Drone near Belarus Border,” September 8, 2025, https://www.reuters.com/world/poland-finds-debris-drone-near-belarus-border-2025-09-08/
[14] CNN, “Poland Scrambles Jets after Reports of Russian Drone Incursion,” CNN International, September 9, 2025, https://edition.cnn.com/2025/09/09/europe/poland-scramble-jets-russian-drone-reports-intl-hnk-ml
[15] AeroTime, “Russian-Made Orlan-10 Drone Crashes in Romania,” March 14, 2022, https://www.aerotime.aero/articles/30476-russian-made-orlan-10-drone-crashes-in-romania.
[16] Reuters, “Romania Finds New Possible Fragments of Russian Drone in Its Territory,” September 9, 2023, https://www.reuters.com/world/europe/romania-finds-new-possible-fragments-russian-drone-its-territory-defence-2023-09-09/
[17] Radio Free Europe/Radio Liberty (RFE/RL), “Romania Finds More Russian Drone Debris,” September 2023, https://www.rferl.org/a/romania-russian-drone-debris/32590895.html
[18] Reuters, “Romania Detects Possible Airspace Breach during Overnight Drone Attack,” September 30, 2023, https://www.reuters.com/world/europe/romania-detects-possible-airspace-breach-during-overnight-drone-attack-ukraine-2023-09-30/
[19] The War Zone, “NATO Fighters Scrambled as Russian Drone Violates Romanian Airspace,” The Drive, September 2023, https://www.twz.com/nato-fighters-scrambled-as-russian-drone-violates-romanian-airspace.
[20] Reuters, “Ukraine Destroys 25 of 38 Drones in Russian Attack, Air Force Says,” July 25, 2024, https://www.reuters.com/world/europe/ukraine-destroys-25-38-drones-russian-attack-air-force-says-2024-07-25/.
[21] Defence-UA, “While Ukraine Repelled Another Blow, Romania Raised 2 F-16s Just to Monitor Russian Drone That Invaded Country’s Airspace,” September 2024, https://en.defence-ua.com/analysis/while_ukraine_repelled_another_blow_romania_raised_2_f_16s_just_to_monitor_russian_drone_that_invaded_countrys_airspace-11785.html
[22] Reuters, “Russian Drone May Have Breached Romanian Airspace,” September 27, 2024, https://www.reuters.com/world/europe/russian-drone-may-have-breached-romanian-air-space-during-overnight-attack-2024-09-27/
[23] Reuters, “Romania Detects Another Drone Breaching Its Territory, Ministry Says,” October 19, 2024, https://www.reuters.com/world/europe/romania-detects-another-drone-breaching-its-territory-ministry-says-2024-10-19/
[24] BBC, “Russian Drone Fragments Found in Romania,” BBC News, September 9, 2023, https://www.bbc.com/news/articles/c80g7g5rmlno
[25] NATO, “Vilnius Summit Communiqué,” July 11, 2023, https://www.nato.int/cps/en/natohq/official_texts_237721.htm
[26] Euronews, “Russian Fighter Jets Violated Estonia’s Airspace, Authorities Say,” September 19, 2025, https://www.euronews.com/2025/09/19/russian-fighter-jets-violated-estonias-airspace-authorities-say
Will Zimmerman is a Senior at American University where he is currently pursuing a bachelors degree in International Studies. His academic focuses have been on East Asia’s and the Pacific and National Security and Foreign Policy. Will’s recent research is centered around the evolving dynamics within NATO as they relate to the Russian invasion of Ukraine.