Donald Trump at second presidential debate: "I know nothing about Russia"

Donald Trump at Sunday night's debate again denied Russia hacked into the Democratic National Committee's emails — despite the U.S. government announcing this week that the Russians were behind the hack — adding in an aside that he knows "nothing about Russia."

"They like to say the Russians did it," Trump said of the hack, which was proven this week. "They think they're trying to tarnish me with Russia. I know nothing about Russia."

Realizing he made a flub, Trump tried to walk it back.

"I know about Russia ... but I have no businesses, no loans from Russia" Trump said — something that's not provable since Trump has not released his tax returns, an unprecedented withholding of documents.

At the first debate, Trump claimed that the DNC hack could've come from "somebody sitting on their bed that weighs 400 pounds."

He's also praised Russian President Vladimir Putin, a dictator who is hostile toward the U.S.

But Trump sought to distance himself from his Putin praise.

"I don't know Putin," he said.