Department of Homeland Security (DHS) Secretary Jeh Johnson admitted Tuesday that there have been successful “cyber-intrusions” into U.S. voter registration rolls.

Johnson made the stunning admission while under questioning from Montana Sen. Jon Tester at a hearing of the Senate Committee on Homeland Security and Governmental Affairs.

“We are seeing, um, a limited number of instances where there have been efforts, um, through cyber-intrusions, to get into the online presence of various state election agencies. And one or two of them have been successful,” Johnson said.

“Others have not. But more broadly, just in the general environment, Senator, we’re in, where we have an increasing level of sophistication with nation-state actors, activists, and so forth, we’ve been out there saying to state election officials, if you need help just ask us for it,” Johnson said.

“They’re getting into the databases and changing the votes? That’s what they’re doing?” Tester asked.

“No, no, I, no, that’s not it,” Johnson said, nervously touching his ear. “There’s been, the matters are under active investigation. I think there’s a limited amount we can say.”

“But, um, what we are seeing are efforts to get into voter registration rolls, the identity of registered voters, things of that nature. Not to change a ballot count,” Johnson added.

“But to change so a person who would normally be registered would not be registered then?” Tester asked. “Is that what we’re talking about? Or to register people who aren’t registered?”

“I cannot say that,” Johnson said. “I cannot say that.”

“Is this coming from one particular country?” Tester pressed on.

“Um, I don’t believe that we have reached a determination of that nature to that extent,” Johnson said.