A 51-year-old man has been arrested in Crimea for allegedly working as a courier for Ukrainian intelligence. The Russian security agency, known as the FSB, revealed the details on Tuesday, making headlines and raising questions about espionage in the region.

The FSB claims that the man, who is a Russian citizen, played a limited role in Ukraine's efforts against Russia. His main task involved picking up several SIM cards from a hidden stash. After receiving instructions from the Ukrainia...