The skies over Eastern Europe have become a testing ground for NATO’s resolve. In September 2025, three Russian MiG-31 fighter jets violated Estonian airspace for 12 minutes—an eternity in military terms. Just days earlier, Russian drones penetrated Polish territory in what officials described as a deliberate provocation. These incidents are not isolated anomalies but part of a disturbing pattern that exposes fundamental challenges facing the alliance as it confronts an increasingly brazen Russia.
The numbers tell a troubling story. Over the past two years, Russian aircraft and drones have violated NATO airspace in Poland at least six times, with similar intrusions reported in Lithuania, Latvia, Romania, Finland, Sweden, and Norway. The worst incident occurred during the overnight violation of Sept. 9-10, 2025, when 19 Russian drones penetrated Polish airspace. Allied aircraft destroyed four drones, and their debris was found over 250 kilometers into Polish territory—marking the most significant incursion to date. Since 2022 there have been dozens of Russian incursions into alliance airspace. What was once considered rare and brief has become routine and increasingly prolonged.
The question NATO faces is deceptively simple yet complex: How do you deter an adversary who seems determined to test your limits without triggering the very war you’re trying to prevent? And how do you do so without splitting the alliance apart?
To this end NATO should agree on and publicize rules of engagement that include shooting down armed crewed aircraft. In support of this, allies should also improve their consultation process for airspace violations and invest in better air defense capabilities.
NATO’s current predicament reveals a paradox at the heart of collective defense. The alliance has responded to Russian violations with stern warnings, emergency consultations under Article 4, and promises to defend its territory with “all necessary military and non-military tools.” Yet with each incursion, the gap between rhetoric and action widens, and the Kremlin takes note, creating a very real credibility problem for the alliance that sows division. Consider the internal tension this challenge creates. Estonia invoked Article 4 after the September fighter jet incident, only to find itself in a reported confrontation with NATO Secretary-General Mark Rutte, who worried that too-frequent invocations of Article 4 would dilute the Washington Treaty’s significance.
But this response carries a risk as well and has begun to strain alliance unity. Eastern European members, who live closest to the Russian threat, understandably see things differently than Western allies operating from comfortable geographic distances. As a result, they have been asking: Do some territorial violations matter more than others? Is there an acceptable threshold of sovereignty infringement?
The credibility problem runs deeper still. Lithuanian Foreign Minister Kestutis Budrys warned that repeated incidents represent “an alarming sign of the spillover” of Russian aggression into NATO territory. Polish Prime Minister Donald Tusk declared his country would shoot down objects violating Polish airspace with “no discussion.” Yet NATO has failed to establish clear, enforceable red lines, leaving Russia to wonder: What exactly are the consequences of the next incursion? And if NATO doesn’t know the answer, how can it expect to deter Moscow?
Setting red lines is no easy matter in an alliance of 32 countries. The September emergency meeting of the North Atlantic Council exposed deep divisions over how to respond to airspace violations. Poland, Estonia, and other Baltic nations pushed for language making clear that future violations—including by crewed aircraft—would be met with force. Germany and other western members urged restraint. The final statement, endorsed by all 32 members, split the difference with carefully calibrated language that satisfied no one ally completely. German Defense Minister Boris Pistorius continues to warn against imprudent responses to airspace violations, lest the alliance fall into Russian President Vladimir Putin’s “escalation trap.”
The challenge is compounded by ambiguity over Russian intent. NATO’s supreme allied commander Europe (SACEUR), Alexus Grynkewich, suggested the Estonian incursion might have been accidental, the result of poorly trained Russian pilots rather than deliberate provocation. It could also be that defense jamming by Ukraine sent the Russian drones into Poland. Needless to say, some NATO members see these explanations as more plausible than others do.
Disunity is precisely what Russia hopes to exploit. Moscow understands that NATO operates by consensus, that it takes time to coordinate responses across multiple capitals with divergent threat perceptions and different population sensitivities. Every Russian airspace violation is a probe, testing not just radar systems and response but political cohesion. Will front-line states act unilaterally if they feel the alliance is moving too slowly? Will western members view eastern concerns as overreaction? These fault lines, once widened, are difficult to repair.
Beyond political challenges, NATO faces uncomfortable technical realities. Rutte cited the defense of Polish territory as evidence that the alliance’s air defense system was successful, but the depth of penetration exposes this claim as false. Moreover, using multimillion-dollar weapons systems such as F-35s against drones costing thousands of dollars is unsustainable. According to the New York Times, Russia has sent more than 34,000 drones into Ukraine since January 2025, dispatching 6,443 drones in July alone. Given the current state of NATO air defenses, the alliance could not cope with a similar barrage during open hostilities.
The alliance’s detection capabilities are especially weak for low-altitude threats from about ground level to around 1 kilometer in altitude. Many smaller drones exploit exactly this vulnerability. The infrastructure NATO built during the Cold War was designed for a different threat—high-altitude bombers and missiles, not swarms of small drones that can be launched from trucks and ships and may come from within the target country, not just from abroad. Adapting to this new reality requires significant investment in layered air defense systems, improved radar coverage, and integrated command and control.
NATO has long recognized it needs better Anti-Access/Area Denial (A2/AD) capability but has failed to develop it. Allied air power remains deficient across the board—even the United Kingdom, one of the alliance’s strongest European members, cannot muster sufficient air defense. NATO’s internal calculations show the alliance has around 5 percent of the capability necessary to defend allied airspace. Commitments to improve NATO’s A2/AD systems were made at the alliance’s 75th anniversary summit in Washington in 2024, and a strategy was largely written by January 2025, but it was silently shelved when the Trump administration took office.
Finally, there’s also the matter of proportionality. Shooting down an unmanned drone carries different risks than engaging a manned fighter jet. The former might be written off as a regrettable but understandable defensive action; the latter could kill a Russian pilot and escalate into broader conflict. Yet both violate the sovereignty of allied nations. NATO allies are well within their legal right to shoot down a Russian aircraft, but doing so could gravely harm alliance cohesion if there is not agreement beforehand.
NATO cannot afford to let these challenges fester. Every unanswered violation chips away at the alliance’s credibility and emboldens further testing. NATO should simultaneously pursue a few courses of action to remedy the challenge.
First, NATO needs clear, pre-established public rules of engagement for airspace violations that empower the SACEUR to defend the alliance. Ambiguity may feel diplomatically safe, but it invites the very miscalculation everyone seeks to avoid. These rules must distinguish between different types of violations while making unmistakably clear that systematic or prolonged incursions will be met with force. Uncrewed systems should always be destroyed, providing doing so would not endanger civilians on the ground. Unarmed crewed airframes should continue to be rapidly intercepted and escorted out of NATO airspace. Crewed airframes carrying missiles or bombs with their transponders turned on and with an incursion depth less than 10 kilometers should likewise be intercepted and escorted out of NATO airspace. But more threatening violations should be met with force. Crewed airframes carrying missiles or bombs with their transponders turned off and penetrating beyond 5 kilometers for over two minutes should be deemed a threat and shot down.
Making these rules public and explicit to the Russian military puts the ball in Putin’s court. The allies should not self-deter on this issue. In 2015, it took the downing of a Russian jet in Turkish airspace to stop Russian incursions. The same measure of resolve might also be necessary for NATO if the Kremlin does not heed a clear, unambiguous warning. The lack of ambiguity shifts the burden of responsibility to Russia, away from NATO. It also preempts potentially unilateral action by a country such as Poland. While the Polish government has both legitimate concerns and the sovereign right to down a Russian military jet violating its airspace, doing so unilaterally may gravely harm alliance cohesion.
Collectively issued rules of engagement will reassure allies such as Poland, Estonia, Finland, and Sweden, while maintaining alliance unity and reducing the risk of escalation with Russia. Achieving consensus on these rules will be an uphill battle. But if pursued carefully it can account for the concerns of countries worried about escalation with the Kremlin.
Second, the alliance must invest urgently in the technical capabilities that members need to detect and respond to low-altitude threats. This includes not just advanced radar systems but also integrated air defense networks that can respond in real time. If NATO is serious about defending alliance territory, it must ensure that there are no blind spots and it must ensure it has cost-efficient capabilities to manage the potential threat.
Third, NATO should establish a standing response mechanism for airspace violations that doesn’t require emergency Article 4 consultations every time. Perhaps this could be a tiered system where certain categories of violations trigger pre-authorized responses, with only the most serious incidents requiring full alliance consultation. A tiered approach would address concerns about diluting Article 4 while giving front-line states confidence that help will arrive when needed. At best, clear and unambiguous rules of engagement will stop further Russian incursions. Increased patrols as part of Operation Eastern Sentry, as well as large-scale interception exercises on the Russian border, should also be done to both reassure allies and deter Russia.
NATO was founded on a simple promise: an attack on one is an attack on all. That promise has preserved peace in Europe for more than seven decades. But promises require action to remain credible, and action requires unity, capability, and resolve. Today, in the skies over Europe, Putin is testing all three.
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