On September 10, nineteen Russian drones entered Poland, marking the largest violation of NATO airspace since the onset of Russia’s full-scale invasion of neighboring Ukraine more than three and a half years ago. Polish Foreign Minister Radosław Sikorski described the attack as an attempt to probe NATO defenses and test the alliance’s commitment to protect its eastern flank. Afterwards, Poland invoked Article 4 of the North Atlantic Treaty initiating consultations with allies, but opted not to push for Article 5, which calls on all NATO countries to provide assistance if a member state’s security is threatened.
Over the past week, numerous Western leaders have condemned Russia’s “reckless” incursion. Meanwhile, NATO has announced the launch of the Eastern Sentry deterrence initiative, with plans for more integrated air defense, intelligence sharing, and new assets. Despite these steps, some believe the response has so far been insufficient. Ukrainian President Volodymyr Zelenskyy has criticized NATO’s “lack of action,” suggesting that European countries need to go further and work on a joint air defense system to create “an effective air shield over Europe.”
If the West fails to credibly deter further Kremlin escalations, this would have potentially disastrous consequences for international security. At stake is not only Ukraine’s survival as a sovereign state, but NATO’s continued existence as the main guarantor of peace and stability in Europe. A conventional Russian invasion of Poland or the Baltic states remains within the realm of possibilities if Moscow is successful in Ukraine. However, a far more likely scenario would be some kind of gray zone aggression on NATO’s eastern flank with the aim of discrediting the alliance’s core commitment to collective security.
This could take many forms. For example, Russia could launch a significantly larger drone attack against Poland. Alternatively, the Kremlin could stage a hybrid cross-border incursion into Estonia, utilizing the same kind of plausible deniability employed during the 2014 seizure of Ukraine’s Crimean peninsula. Moscow’s goal would be to demonstrate that the NATO alliance lacks the resolve to act on its collective security commitments, while remaining below the threshold that could trigger a full-scale war.
Even prior to the recent appearance of Russian drones over Poland, there were already ample indications that the scale of the threat posed by the Putin regime was not fully understood in Western capitals. Recent diplomatic efforts to end the invasion of Ukraine via some form of compromise peace deal suggest a fundamental misunderstanding of Russia’s maximalist war aims. Putin’s ambitions extend far beyond limited territorial gains in Ukraine; any attempt to appease him with “land swaps” will merely whet his imperial appetite and encourage further aggression.
Members of the so-called Coalition of the Willing led by France and the UK have spoken recently of providing Ukraine with “robust” security guarantees, but only after a ceasefire is in place. This gives the Kremlin dictator no incentive to back down. While Putin’s recent summer offensive in Ukraine has failed strategically, Russia continues to make marginal gains on the battlefield while mercilessly striking Ukrainian cities and civilians with drones and missiles. It is therefore imperative to compel the Kremlin to agree to a ceasefire first, separating this from discussions over security guarantees while retaining a commitment to both.
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A far more united, assertive, and multi-pronged approach is required in order to deter Russia. Western governments must make full use of the extensive economic leverage at their disposal. Washington and Brussels should seize Russia’s frozen assets and implement tougher sanctions that drastically cut Russia’s income from oil exports, including measures targeting Moscow’s shadow fleet of tankers. Applying additional secondary sanctions on foreign financial institutions that facilitate the purchase of Russian oil will force buyers like India and China to comply with US sanctions or risk losing access to the global financial system.
At the same time, the US and Europe must ensure Ukraine becomes a “steel porcupine” capable of defending itself and deterring future Russian aggression on its own. This should involve guaranteed weapons deliveries, an end to all restrictions on Ukrainian long-range strikes inside Russia, increased intelligence sharing, and enhanced industrial cooperation between Western and Ukrainian defense companies, especially in terms of drone technologies and electronic warfare.
This combination of intensifying economic pressure on Russia and increased military support for Ukraine could set the stage for a ceasefire agreement. If this is achieved, the West must then unilaterally implement security guarantees and deploy troops from as many countries as possible to Ukraine to ensure maximum deterrence. Any deployments should take a layered approach. The initial step would be a monitoring mission on the line of contact, followed by the deployment of soldiers across Ukraine, along with air and naval patrols.
While American troops will almost certainly not be involved on the ground in Ukraine, it is vital that US President Donald Trump sticks to his commitment to back any reassurance force with continued intelligence, surveillance, and reconnaissance support, along with a potential aviation component. The Trump administration has successfully encouraged NATO members to spend more on defense and support Kyiv, but Trump’s skepticism toward alliances and his often ambiguous position on Ukraine increase the likelihood of a Russian challenge to NATO’s Article 5 in the near future.
Putin’s latest escalation in the skies over Poland is an unmistakable signal that NATO’s credibility is under threat. In order to reduce the potential for a larger European war, a new approach to engagement with the Kremlin that projects strength and resolve is clearly required. Failure to act accordingly will place the entire international security architecture in question, including the foundational principle that borders cannot be changed by force.
Zahar Hryniv is a Young Global Professional at the ’s Eurasia Center.
The views expressed in UkraineAlert are solely those of the authors and do not necessarily reflect the views of the , its staff, or its supporters.
The Eurasia Center’s mission is to enhance transatlantic cooperation in promoting stability, democratic values, and prosperity in Eurasia, from Eastern Europe and Turkey in the West to the Caucasus, Russia, and Central Asia in the East.
Image: Russian President Vladimir Putin observes the Russia-Belarus joint military exercises, codenamed Zapad-2025 (West-2025), at the Mulino training ground in the Nizhny Novgorod region, Russia. September 16, 2025. (Sputnik/Mikhail Metzel/Pool via REUTERS)
