Western security officials believe that two incendiary devices found on DHL aircraft en route to Canada and the United States last summer were part of a Russian sabotage plot.
The explosive instruments were discovered in July after they ignited at separate logistics facilities in Leipzig, Germany, and Birmingham, England.
Forensic analysis of the recovered materials traced the source of the fires to compromised electric massagers, which had been shipped via the German delivery service from a location in Lithuania.
Lithuanian law enforcement officials told The Wall Street Journal that they arrested an individual suspected of sending the dangerous items on behalf of Russia's intelligence services.
Poland’s National Prosecutors Office joined the investigation after announcing charges against four additional suspects. The alleged accomplices are said to have taken part in the operation to assess the feasibility of sending similar components to the destination countries.
A spokesperson for DHL, Dirk Heinrichs, emphasized in a statement his company is "fully cooperating with the relevant authorities to protect our employees, our network, and our customers' shipments."
