We do not know whether the Kremlin today knows, or can guess, the nature of the “significant intelligence capability” that the U.S. government has. Before Russia’s interference in the 2016 U.S. election, the CIA reportedly had a human source close to Putin, who gave it the confidence to conclude that Putin had personally ordered the intelligence operation against the United States. Following in Gordievsky’s footsteps, the CIA apparently exfiltrated that source from Russia. The CIA may have done it again now: who knows. If the U.S. intelligence capability is unknown in Moscow, Biden may be going further than Kennedy by risking a still-secret source or method to similarly “stick it” to Putin and reveal details about his ambitions.

There is some evidence to suggest that U.S. intelligence came from signals intelligence (SIGINT): intercepted communications of Russian-allied forces chatting about Ukraine invasion plans. If the capability is indeed derived from signals intelligence or technical cyber collection, it may have a shorter lifespan, which could lessen the cost of revealing it. If it is derived from a human source, however, it would raise the threshold for releasing its details, because a life would literally be at stake. Russia’s intelligence services have a long tradition of executing spies in their ranks. The KGB identified Penkovsky as a Western spy, arrested him, and executed him: most likely with a ritual bullet to the back of his neck in the basement of KGB headquarters, though rumors swirled that he was tied up with chicken wire and cremated alive in a furnace as a warning to other officers. MI6 decided to exfiltrate Gordievsky when it became clear that his life was at risk in Moscow.