New Delhi, Aug. 26 -- When Andrei Fedorov spoke to BBC Newsnight this week, he chose his words with the careful imprecision of a man who wanted to be understood without being quoted too precisely. The former Russian deputy foreign minister did not say Russia would attack British drone factories. He said something might happen to them.

pausing before the qualifier - "not by Russia, but from unknown sources."

The distinction between Russia and "unknown sources" is one Britain has been wrestling with for years in Estonia, in Germany, in the skies above the North Sea. The threat is familiar in its deniability and in the seriousness with which European security services take it. What is new is its directness. Fedorov did not say British fact...