In the months before the election, the military’s Cyber Command began a campaign to deter the Russians behind the 2016 influence campaign. They sent messages to Russian operatives saying they had been identified and warned them to cease their efforts.

Cyber Command, the National Security Agency and the F.B.I. also tried to identify fake accounts and Russia-backed trolls who were spreading Moscow’s propaganda, passing that information along to technology companies so the accounts could be removed.

The New York Times first reported those Cyber Command operations in October. This month, The Daily Beast published an interview with Yevgeny Zubarev, the director of Russia’s Federal News Agency, in which he said he had been targeted by Cyber Command. “The United States Cyber Command writes to me to say that what I am doing is wrong, that their job is to fight trolls,” Mr. Zubarev told The Daily Beast

The results of those efforts, and much broader public understanding of Russian techniques, helped contribute to a less-effective campaign, according to Defense Department and other American officials.

Government officials said they had hoped American resilience and resistance to the Russian techniques might be growing. A pair of reports commissioned by the Senate Intelligence Committee and released this week provided new information about how Russians sought to inflame American opinion and exacerbate existing divisions in the country.

One report released Monday outlined how the Russian campaign aimed to drive down African-American participation in the 2016 election.

Participation in the midterms was up with both parties, and it was not clear if the Russians tried to drive down participation with particular groups of people or if they abandoned that effort during this vote.