There was no evidence that any of the registration rolls were altered, but the DHS is still treating it seriously. "2016 was a wake-up call and now it's incumbent upon states and the Feds to do something about it before our democracy is attacked again," said Jeh Johnson, who was DHS secretary during the Russian intrusions. "We were able to determine that the scanning and probing of voter registration databases was coming from the Russian government."
NBC News had reached out to the aforementioned 21 states, but five states responded that they weren't attacked. Manfra defends the department's findings, stating that it is a "snapshot in time with the visibility that the department had at that time."
This is in line with several reports in recent months that claim that Russians had hacked into US voter systems. Though there's no indication that the Russians actually tampered with anything, there was at least one incident where voter information was altered, even if it's unclear who actually did it.
Much of this has prompted Johnson to declare that the country's election systems should be considered "critical infrastructure" and should thus be under the jurisdiction of the DHS. Some states have voiced that they didn't want DHS involvement because they thought it was federal intrusion -- a few swing states didn't want DHS to protect their voting machines in 2016, for example. Johnson told NBC News that he thought state officials that refuse federal help were "naïve" and "irresponsible to the people that [they're] supposed to serve."