The United States Cyber Command launched an offensive campaign to silence one of Russia’s most notorious troll operations on the day of the 2018 midterm elections, according to a new report by The Washington Post. The operation targeted the Internet Research Agency, a private company linked to the Kremlin and often used for disinformation campaigns.

The US operation seems to have taken the IRA entirely offline during Election Day, to the point that many employees complained to systems administrators that they were unable to access the internet, according to the Post’s sources. “Part of our objective is to throw a little curve ball, inject a little friction, sow confusion,” one unnamed official told the Post.

It’s one of the most aggressive publicly reported campaigns the cyber command has yet taken, and the legal status of such actions remains in flux. In theory, infrastructural attacks against agents of a foreign government could have significant diplomatic repercussions, and run the risk of being taken as an act of war. But in practice, these actions are rarely officially attributed and political blowback is typically minimal.

In June, the Pentagon expanded the cyber command’s authority to include more offensive campaigns, in contrast to what was previously a largely defensive mission. Those changes were made just months before the reported Election Day campaign.

The IRA has been at the center of much of the US response to Russian election interference in 2016. In February 2018, special counsel Robert Mueller indicted 13 Russians linked to the IRA for crimes related to election interference, citing fake Facebook posts used to “organize and coordinate US political rallies in support of president-elect Trump.”

Today’s story is the first explicit indication of an Election Day operation against the IRA, but general countermeasures were widely discussed during the 2018 campaign season. On the day of the election, US intelligence agencies issued a public warning that foreign intelligence agencies were still attempting to manipulate public sentiment.

“Americans should be aware that foreign actors – and Russia in particular – continue to try to influence public sentiment and voter perceptions through actions intended to sow discord,” the announcement read. “Such actions are a threat to our democracy, and identifying and preventing this interference is one of our highest priorities.”