If the FSB did discover that Mr. Steele was poking around for information, it hardly could have resisted using the gravitas of a retired MI-6 agent to plant false information. After hacking the DNC and senior Democratic officials, Russian intelligence chose to pass the information to WikiLeaks, most likely to capitalize on that group’s “self-proclaimed reputation for authenticity,” according to a 2017 report from the U.S. Office of the Director of National Intelligence. Simultaneously the Kremlin was conducting influence operations on Facebook and other social-media sites.

The pattern of such Russian operations is to sprinkle false information, designed to degrade the enemy’s social and political infrastructure, among true statements that enhance the veracity of the overall report. In 2009 the FSB wanted to soil the reputation of a U.S. diplomat responsible for reporting on human rights. So it fabricated a video, in part using real surveillance footage of the diplomat, that purported to show him with a prostitute in Moscow.