John Ratcliffe, the C.I.A. director, delivered an urgent message to Aleksandr V. Bortnikov, the head of Russia’s F.S.B. intelligence service this week in a secret visit to Moscow.
Russian troops are trying to infiltrate the vast, overgrown reservoir basin of a dam they blew up three years ago as Ukrainian soldiers hunt them at close quarters.
Ukrainian soldiers of the Bratstvo Battalion unloading their equipment after making their way out of the Kahkovka reservoir basin, completing their weeks-long mission, in July.