Wednesday morning's incursion of Russian drones into Polish airspace led to jets being scrambled, an emergency government meeting being called - and concerns that Europe and NATO's resolve against Moscow may not be up to the test.
Poland's Prime Minister Donald Tusk said Polish airspace was violated 19 times and at least three drones were shot down by Warsaw's jets, aided by Dutch F-35s and an Italian early warning aircraft.
Russia has pushed back against accusations that the incursion was deliberate – though it also stopped short of denying its drones had trespassed sovereign Polish airspace.
No objects on Polish territory were planned to be targeted, Moscow said.
But European officials have forcefully batted off suggestions the act may have been unintentional.
There is no evidence whatsoever that this amount of drones flew over this route over... Polish territory by accident, Germany's Defence Minister Boris Pistorius said, while his Italian counterpart Guido Crosetto called the overnight events in Poland a deliberate attack with the double aim of provoking and testing.
Although Poland has experienced several violations of its airspace since neighbouring Ukraine was attacked by Russia in February 2022, this latest incursion - sizeable, and deep into Polish territory - sparked real nervousness in Warsaw.
Tusk warned that Poland was at its closest to open conflict since World War Two. He also requested invoking Article 4 of the NATO treaty, which allows member countries to start a discussion with allies about threats to their security.
Some experts and analysts are divided over Russia's motivations.
To some, the drones – some of which flew in the direction of Rzeszow airport, a major logistical hub for defence supplies and humanitarian aid bound for Ukraine – may have had reconnaissance purposes, with poor guidance leading to accidental airspace trespass.
Dr. Marina Miron, a defence researcher at Kings College London, believes GPS spoofing may have been responsible for the drones crossing into Polish airspace and cautioned against drawing conclusions based on snippets of information. It can lead [the incident] to appear as something it is not, Dr. Miron added.
Many others believe, however, the relatively high number of drones flown into Polish airspace clearly demonstrates that the attack was deliberate.
Justin Bronk of the defence think tank Rusi noted that previous incursions were single or very small numbers that were more easily explained by guidance system malfunctions.
Justin Crump, CEO of the risk and intelligence company Sibylline, stated that the drones in question appear to be Russian-made cheap, long-range drone Gerberas which can be used as decoys to distract defences as part of Russia's increasing grey zone actions against NATO.
The lack of warheads on the Gerberas drones employed on Wednesday makes them appear less threatening and allows Russia to play down the action, Mr. Crump added.
Poland will now need to review the incident and share the findings with its allies.
Whether deliberate or not, the unprecedented incident will provide valuable information to Moscow on the type of response it can expect from the West should it ever decide to launch an attack on NATO countries, as many European leaders have said they expect it to do in the near future.
It is a test for Europe and for NATO regardless of Russia's intent, said Keir Giles, a senior fellow in the Russia and Eurasia program at Chatham House.
Expressions of condemnation rather than a robust response will be just as encouraging to Russia if it was an accident as if it were a deliberate provocation, Mr. Giles added.
He said a sky shield to protect airspace over Ukraine would prove to Russia the West is serious about ensuring air threats are intercepted. However, such a plan - involving European countries deploying fighter jets and pilots - has led to fears of accidental confrontation with the Russians and has not yet materialized despite being proposed since 2023.
The US's reaction to the incident in Poland will also be awaited – and closely followed.
Some US lawmakers in both the Democrat and Republican camps condemned the attack soon after it occurred.
However, as of Wednesday evening, US President Donald Trump had only acknowledged the events in Poland through a social media post. What's with Russia violating Poland's airspace with drones? Here we go! he wrote without elaborating further.
The cryptic post reflects his ambiguous relationship with Russia and its President Vladimir Putin.
As leaders scramble to present a show of unity and strength, Europe – concerned about US commitment to the security of the continent since the start of Trump's second term – will be watching the US's next move just as closely as Russia.
A sign of weakness and failure to impose costs and consequences will confirm for Moscow that they can continue to escalate without fear of the outcome, Mr. Giles said.
Additional reporting by Matt Murphy and Paul Brown
