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Poland has detained four people suspected of being involved in test runs for a Russian plot to detonate parcel bombs on US-bound transatlantic flights.
Warsaw launched an investigation after Germany said last month that it narrowly avoided a plane crash when a parcel destined for an aircraft’s hold burst into flames before the flight at a DHL logistics centre in Leipzig.
The UK’s counterterrorism police are also investigating the origins of another package that caught fire at a DHL depot in Birmingham in July.
According to two European security officials briefed on intelligence assessments, the European incidents, which involved packages sent from Lithuania, were designed in part to test whether the same methods could be used to attack flights to the US.
“Russian military intelligence” was the “source” of the attacks, Kęstutis Budrys, national security adviser to Lithuania’s President Gitanas Nausėda, told local media on Tuesday.
Dmitry Peskov, president Vladimir Putin’s spokesman, told reporters on Tuesday the claims were “muddled misinformation”, according to state television.
The Polish prosecutor’s office said the four suspects were detained as part of an international investigation launched in August and co-ordinated with other European countries.
It added that the probe was continuing and international arrest warrants had been issued for another two people believed to be involved in the parcel bombing plan.
The Wall Street Journal has previously reported that the devices in the packages were electric massagers implanted with a magnesium-based flammable substance, which security officials believe were part of a wider Russian plot.
Polish prosecutors said on October 25 that the latest arrests were related to parcels that “spontaneously ignited or detonated during land and air transport” to EU countries and the UK. They added that the group’s goal was allegedly “to test the transfer channel for such parcels, which were ultimately to be sent to the US and Canada”.
The prosecutor’s office would not give further details on those arrested, but the investigation is also looking at planned attacks on infrastructure ranging from airports to industrial facilities.
Polish, German and British officials have not directly accused Russia over the parcel bombs but intelligence officials suspect the Kremlin has sponsored proxies to prepare sabotage attacks.
Bruno Kahl, head of Germany’s foreign intelligence service, said last month that the Kremlin’s willingness to take covert action had reached a “previously unknown level”.
Ken McCallum, head of Britain’s domestic intelligence agency MI5, also warned last month that Russia’s GRU military intelligence unit was on a “sustained mission to generate mayhem on British and European streets: we’ve seen arson, sabotage and more”.
There has been a spate of Russian-linked sabotage incidents across Europe this year, including allegedly Russian-backed arson attacks on a Ukrainian-linked warehouse in the UK and an Ikea warehouse in Vilnius.
Last month, Polish foreign minister Radosław Sikorski ordered the closure of the Russian consulate in the western city of Poznań, accusing the country’s officials of helping prepare acts of sabotage.
Sikorski cited a recent Polish court case in which a Ukrainian citizen confessed he had been planning arson attacks on behalf of Russia.
A spokesperson for DHL said: “We are aware of the two mentioned incidents involving shipments in our network. We are fully co-operating with the relevant authorities to protect our people, our network and our customers’ shipments.”
A US official said: “At this time, there is no current active threat targeting US-bound flights”, adding that, “as stated in the 2025 Homeland Threat Assessment, the US continues to be vigilant against threats to the aviation and air cargo systems”.
The German and British domestic intelligence agencies declined to comment.
Additional reporting by Laura Pitel and Max Seddon in Berlin and Felicia Schwartz in Washington