In brief: In a show of online force, the US Cyber Command was able to disrupt the internet access for the infamous Russian Internet Research Agency on the day of the 2018 midterm election. It appears that this attack was more to send a message than to cause damage to the IRA.
Individuals familiar with the issue told The Washington Post that "they basically took the IRA offline" for a day or so. This was done in an effort to prevent Russian trolls from spreading false information while Americans were voting. It is also believed that US defense officials gathered intelligence showing IRA trolls were so frustrated with the blockage, that they complained to their system administrators.
The IRA is well known for its role in influencing the 2016 Presidential Campaign and sowing discord on social media sites. US federal agents believe the IRA is financed by Yevgeniy Prigozhin, a Russian oligarch with close ties to Putin.
Cybercom was granted additional powers to expand its scope of attacks by President Trump and this operation was the first real test of their new strategy. At the time it took place, the attack was not publicized, but now that it has been made public, it appears to have accomplished its goal.
This is not the first time that the IRA has been a target of the US cyber campaigns. Several months ago, members of Cybercom direct messaged suspected IRA trolls instructing them not to interfere in further elections. US intelligence operatives shared the real names and online usernames of the trolls as a warning that they were being watched.
Officials aren't sure what effect this recent attack will have in the long term, but hope that it will show that the US is serious about preventing further Russian interference.