WASHINGTON, Aug. 26 -- When the American C-17 military transport touched down at Vnukovo airport outside Moscow last week, the Kremlin's intelligence watchers were among the first to notice. A diplomatic motorcade pulled away from the tarmac, and within hours, several European intelligence services had logged the flight. The passenger, eventually confirmed to be CIA Director John Ratcliffe, had arrived in a city that no American official of his standing had visited in years.

The significance of who made the trip matters as much as that it happened at all. A CIA director does not fly to Moscow to exchange pleasantries. The last time one made the journey, William Burns sat across from Russian officials in November 2021, in the weeks before...