BERLIN >> European and U.S. intelligence officials believe Russia is behind a plan that would ultimately place incendiary devices on planes to North America through air cargo shipments, according to people familiar with the matter.

Authorities are taking the incidents seriously, and intelligence agencies are expecting Moscow to try and stage similar acts of sabotage in the future, one of the people said. They asked not to be named discussing the intelligence matter.

Poland’s National Prosecutor’s Office has said in a statement on its website that it’s investigating the alleged involvement of a foreign intelligence service in sabotage activities on the territory of Poland and other European Union members states and the U.K. but didn’t specify Russia as the perpetrator. The Wall Street Journal reported earlier Monday on Moscow’s alleged goal of ultimately targeting the U.S.

Poland’s interior minister said the efforts fit Russia’s pattern.

“The year 2024 brought various acts of sabotage in Poland and other European countries,” Tomasz Siemoniak said Monday. “Our intelligence services and prosecutors have no doubt that Russian clients are behind this. The attempts to place explosives into courier shipments fit into the logic of Russian sabotage and do raise the threat up to a new level.”

As part of the probe launched on Aug. 5, authorities have arrested four people linked to a sabotage group, whose activities included sending parcels containing camouflaged explosives and dangerous materials via courier companies to countries in the EU and the U.K.

The parcels would ignite or detonate during land or air transport. “The group’s goal was to test the transfer channel for this type of shipments, which were ultimately to be sent to the U.S. and Canada,” according to the statement.

Alexa Lopez, a spokeswoman for the U.S. Transportation Security Administration, said in a statement that “over the past several months, as part of a multilayered security approach, TSA worked with industry partners to put additional security measures for U.S. aircraft operators and foreign air carriers regarding certain cargo shipments bound for the United States.”

Governments across Europe have been raising alarm over a growing threat of Russia-sponsored acts of sabotage and destabilization since the Kremlin launched its full-scale invasion of Ukraine more than two and a half years ago. Russia has repeatedly denied involvement in such efforts.

Earlier this year, the U.S. warned its allies that Russia is targeting cargo shipping companies as it seeks to disrupt Ukraine’s partners, according to people familiar with the matter. At the time, the Russian Foreign Ministry didn’t reply to a request for comment.

German security authorities have concluded that their country only narrowly escaped a plane crash caused by an incendiary package in an air foreign parcel that was probably planted by Russia. By chance, they said, the parcel caught fire on the ground during a delay at a DHL logistics center in July in Leipzig and not during a flight.

Last month, Poland ordered the closing of Russia’s consulate in the western city of Poznan due to alleged sabotage attempts. Russian Foreign Ministry spokeswoman Maria Zakharova condemned the move as hostile and pledged a forceful response, according to the state-run RIA Novosti agency.

Poland has become the main thoroughfare for western military aid heading to Kyiv since the start of the conflict. Still, there are tensions between the the two countries, with Poland’s top diplomat making a show last month of putting the brakes on Ukraine’s ambitions for fast-track ascension to the European Union.

A DHL spokesperson said the company is cooperating with authorities. A spokesman for the Interior Ministry in Berlin declined to comment on the case, citing the ongoing investigation.