“Dismissing it as fake news misses the point,” said a Western security official who requested anonymity in discussing ongoing investigations into the Russian campaign. “It’s about undermining key pillars of democracy and the rule of law.”

Variations on the technique existed during the Cold War, when the Soviet Union used propaganda to create alternative realities. In the early years of President Vladi­mir Putin’s rule, Russian officials and state-owned broadcasters promoted false narratives to explain the death of Alexander Litvinenko, the former Russian security official who died in 2006 after being exposed to a radioactive toxin in London.

But the disinformation campaigns now emanating from Russia are of a different breed, said intelligence officials and analysts. Engineered for the social media age, they fling up swarms of falsehoods, concocted theories and red herrings, intended not so much to persuade people but to bewilder them.

“The mission seems to be to confuse, to muddy the waters,” said Peter Pomerantsev, a former Russian-television producer and author of “Nothing Is True and Everything Is Possible,” a memoir that describes the Kremlin’s efforts to manipulate the news. The ultimate aim, he said, is to foster an environment in which “people begin giving up on the facts.”