Several NATO members are sending troops, artillery, and air defense systems to secure its eastern flank after what Poland called an unprecedented Russian drone incursion into its airspace.
In the early hours of Wednesday, three Russian drones were shot down after crossing into Polish airspace.
Other drones crashed to the ground and were later found across eastern Poland.
Poland has requested a UN Security Council session about the incident, which will take place on Friday at 19:00 GMT.
In response to the drone incursion, the Netherlands and the Czech Republic said they would send defenses to Poland, while Lithuania would receive a German brigade and greater warning of Russian attacks on Ukraine that could cross over.
Germany also said it would 'intensify its engagement along NATO's eastern border' and extend and expand air policing over Poland.
Later, France's Emmanuel Macron announced the country would send three Rafale fighter jets to help protect Poland's airspace.
We will not yield to Russia's growing intimidation,' Macron said.
Polish Defence Minister Wladyslaw Kosiniak-Kamysz listed offers of support, revealing that the Dutch would deploy air defense systems, artillery, and 300 troops, while the Czech would send helicopters and 100 soldiers.
He added that the French and British could deploy aircraft to secure NATO's eastern flank.
Poland has repeatedly heard words of solidarity and empty gestures throughout its history, Kosiniak-Kamysz stated. Today, we have concrete declarations.\
Although Russian drones and missiles have trespassed into some NATO member countries before, this was the most serious incident since the full-scale Russian invasion of Ukraine in February 2022.
The Kremlin has refrained from commenting on the claims that Russia deliberately sought to stoke tensions in Poland.
However, many Polish and European leaders believe the incursion was deliberate. This Russian provocation is nothing more than an attempt to test our capabilities, Polish President Karol Nawrocki remarked, echoing sentiments from German and French leaders.
Experts remain divided on whether Moscow intended to launch the drones into Poland. NATO's top military commander Alexus Grynkewich has acknowledged it is not yet clear whether the act was intentional, as the exact number of drones that crossed into Polish airspace is still to be determined.
In reaction to the rising concerns, Poland plans to set restrictions for drones and small air traffic along its eastern borders with Belarus and Ukraine. Latvia announced its eastern airspace would be closed for a week.
Ukraine's President Volodymyr Zelensky offered to provide guidance and training to Western military representatives to fend off Russian aerial attacks as Ukrainian forces do regularly. He also called for a joint air defense system to shield Europe from Russian threats.
Compounding tensions in the region are significant joint military exercises between Belarus and Russia, dubbed Zapad 2025, set to commence on Friday.
Poland is preparing to close its border at midnight local time on Thursday for national security reasons in response to the very aggressive Zapad maneuvers.
Russian authorities have urged Poland to reopen its border with Belarus, warning that its closure will significantly impact businesses and freedom of movement.
Previous Zapad exercises, held prior to the escalation of the war in Ukraine, involved around 200,000 troops. This year's drills are expected to be smaller in scale, involving up to 30,000 troops in total.
The response from US President Donald Trump regarding the drone incident has been minimal, stating, What's with Russia violating Poland's airspace with drones? Here we go! without further elaboration.
Polish President Nawrocki indicated ongoing talks with his US counterpart reaffirmed allied unity in the wake of these tensions.
