Russia suspected in plot to target cargo planes in Europe and the U.S.

European security officials have linked suspected Russian operatives to a plot to smuggle incendiary devices onto a cargo plane in Germany, in what investigators believe may have been a trial run for future attacks targeting North America-bound aircraft.

An international probe that began after one of the devices caught fire prematurely in July determined that the plotters also sent packages without the flammable contents to U.S. and Canadian addresses, in an apparent test to see if the parcels could be successfully delivered, according to European security officials.

The scheme to spark fires aboard aircraft was being seen as a provocative and particularly dangerous escalation in an alleged sabotage campaign directed by Moscow against NATO countries helping Ukraine defend itself against a Russian military invasion. Russia has denied any connection to such plots.

The new revelations come 10 days after Poland’s National Prosecutor’s Office announced the arrests of four people as part of an ongoing investigation into “activities of foreign intelligence through acts of sabotage” in Poland and other European Union member states, according to a statement. Arrest warrants were issued against two other individuals who were still at large.

The suspects were accused of sending parcels containing “disguised explosives and dangerous materials” using international courier services, the prosecutor said.

“The group’s goal was also to test the transfer channel for such parcels, which were ultimately to be sent to the United States of America and Canada,” the statement said.

Three European security officials confirmed that the parcels had been linked to a sabotage plot involving alleged Russian operatives or their proxies. The officials, speaking on the condition of anonymity to discuss an active investigation, said it was unclear whether the scheme was directed by the Kremlin or by lower-level intelligence officials.

One of the European officials said the plot appeared to be in the early stages and was relatively unsophisticated.

New details of the investigation were first reported on Monday by the Wall Street Journal.

German law-enforcement officials were initially alerted to the plot when a fire broke out in a Leipzig, Germany, cargo hub operated by the German-based international courier DHL. The blaze was traced to a package containing an electronic massager that had been altered with the addition of a highly flammable form of magnesium.

The package had originated in Lithuania and caught fire during a stopover. It was marked for delivery to a fake address in Birmingham, England, according to a German security official.

Fortunately, the package “ignited on the ground rather than during a flight, preventing what could have been a catastrophic situation,” the official said. “Had it exploded in the air, it could have resulted in a crash, with debris potentially injuring people on the ground.”

According to a second European official familiar with the investigation, the same sender shipped packages to U.S. and Canadian addresses, without the flammable contents.

“These packages were deemed to be trial runs by the sender, who wanted to test how far they could reach,” the official said.

Biden administration officials decline to address details of the alleged firebombing attempt. A senior U.S. official said there are “no current active threats involving U.S.-bound flights.”

A spokesperson for the U.S. Transportation Security Administration said in a statement that the agency had implemented additional security measures to prevent sabotage involving U.S.-bound cargo shipments.

“We continually adjust our security posture as appropriate and promptly share any and all relevant information with our industry partners, to include requirements and recommendations that help them reduce risk,” the spokesperson said.

Russian officials could not be reached for comment on Monday. Kremlin spokesman Dmitry Peskov previously told The Washington Post that the allegations of Russian sabotage activity were “no more than a stoking of Russophobic hysteria.”

- - -

Greg Miller, Ellen Francis and Ian Duncan contributed to this report.