Vladimir Putin is continuing to prepare for a potential future Russian war against NATO, experts say, as Europe fears an armed attack by Moscow. The European Commissioner for Defence and Space, Andrius Kubilius, said in a speech on Sunday that intelligence services, including from Germany, Denmark, Finland and the Netherlands, suggest that Putin could be ready to test Article 5 of NATO – which states that an armed attack against one member is considered one against all members – during next two to four years, before 2030.

He called an attack scenario “day X”, adding that Europe would “face the aggression of a Russian battle-tested army, which is now much stronger than it was back in February 2022, and is able to use millions of drones”. Saboteurs damaged at least two segments of a Polish railway on a route to Ukraine, officials believe. Polish police said that a train conductor observed damage to a portion of the Lublin-Warsaw railway line near Życzyn on the morning of November 16, the Institute for the Study of War (ISW) noted in its daily report on Putin’s full-scale invasion of Ukraine.

The Polish prime minister, Donald Tusk, confirmed on November 17 that the explosion destroyed portions of the Lublin-Warsaw railway line near Mika and Lublin.

The ISW wrote: “Polish authorities have not attributed the explosions to a specific actor as of this writing… It is unclear whether this incident on the Warsaw–Rzeszów railway line is connected to the incidents on the Warsaw-Lublin line.

“The Lublin-Warsaw and Warsaw–Rzeszów railway lines support Western military assistance deliveries to Ukraine.

“The rail line explosions come against the backdrop of Russia’s intensifying “Phase Zero” campaign to destabilise Europe, undermine NATO’s cohesion, and set the political, informational, and psychological conditions for a potential future Russian war against NATO.”

Chief of the Polish general staff, General Wiesław Kukuła, said the incident meant the region was in “pre-war status”.

“The adversary has begun preparing for war,” he said, Rzeczpospolita reported.

“They are building a certain environment here, which is intended to create favourable conditions for potential aggression on Polish territory.”

General Kukuła added: “This is typical of 1939, but it actually preceded many armed conflicts, and also occurred at a time when these armed conflicts did not occur.

“I emphasise once again: what matters most today is our attitude, our reaction.”