Russia has been plotting to place incendiary devices on cargo planes in Europe and even performed a test run this summer, setting off fires at shipping hubs in Britain and Germany, according to three Western officials briefed on intelligence about the operation.

The effort represents a potentially significant escalation of the Kremlin’s sabotage operations against Western adversaries.

The goal of the plot, orchestrated by Russia’s military intelligence agency, the GRU, is not entirely clear, according to two of the officials, all of whom spoke on condition of anonymity to discuss sensitive intelligence matters. It could have been what ultimately occurred: to set fires with incendiary devices placed at logistics hubs belonging to the package shipping company DHL, perhaps meant to instill fear or deliver a warning.

But Western intelligence agencies are also investigating whether Moscow intended something more ambitious, and menacing, such as destroying planes on American runways, setting off bombs at U.S. warehouses or even blowing up aircraft midair.

The operation is an effort by Russia’s president, Vladimir V. Putin, to inflict damage on the West for its support of Ukraine’s military, officials said. The Kremlin’s goal appears to be to shake Western backing for Ukraine or, failing that, exact a price for it.

In the first two years of the war with Ukraine, the Kremlin largely avoided directly provoking Kyiv’s allies, particularly those belonging to NATO, officials said, fearful of a dangerous escalation. Today, any such reticence appears to have dissolved, they said.