Intelligence agencies had assessed that the Russian troll farms that create and spread disinformation in the United States and Europe were likely to step up their disinformation activity on the day of the vote and while votes were being counted.

Officials said the Election Day operations were part of a larger campaign led by United States Cyber Command and the National Security Agency to secure the midterm vote. Those operations began with a campaign of direct messages sent to Russian operatives who had created disinformation and propaganda aimed at sowing dissent and undermining confidence in American voting systems. Those direct messages were aimed at deterring the creators of propaganda.

The Election Day operation, reported Tuesday by The Washington Post, was conducted under new authorities authorized by the White House. The new authorities, officials said, have sped up decision making, ensuring that bureaucratic concerns do not get in the way of taking action.

Intelligence officials have said it is difficult, if not impossible, to use cyberoperations to take an adversary off line permanently. Cyberweapons typically exploit unpatched vulnerabilities in software. Given time, the target of an operation can find workarounds or fix software problems, restoring its internet connectivity or computer operations.

Because of that, officials said, the operations against the Internet Research agency were designed to last only for a limited number of days.