Russia was responsible for sending two incendiary devices to DHL logistics hubs in Germany and the United Kingdom in July as part of a wider sabotage campaign to possibly start fires aboard aircraft bound for North America, a Western security official told NBC News.
The Wall Street Journal first reported on the suspected plot.
Polish authorities have arrested four people and are searching for two more in connection with the case, according to government officials and Polish media.
DHL said in an email that it is “aware of two recent incidents involving shipments in our network” and that it is cooperating with investigators.
The U.S. Transportation Security Administration said it has bolstered air cargo screening over the past several months.
A U.S. official said federal authorities remain vigilant against threats to aviation and air cargo systems and added, “At this time, there is no current active …