Hillary Clinton brought Russian President Vladimir Putin into Monday night's presidential debate when she was asked about cyber warfare and high-profile hacks on American interests.
"Increasingly, we are seeing cyber attacks coming from states," Clinton said. "The most recent troubling of these has been Russia.
"There's no doubt now that Russia has used cyber attacks against all kinds of organizations in our country, and I am deeply concerned about this and I know Donald is very praiseworthy of Vladimir Putin, but Putin is playing a tough, long game here."
Clinton then mentioned the recent hack on the Democratic National Committee. Experts said there were signs that Russia was to blame in that case.
In July after the hack was made public, Republican presidential candidate Donald Trump challenged Russia to "find the 30,000 emails that are missing," referencing the emails that were deleted from Clinton's private email server.
Clinton said Monday she was "shocked" at Trump's comments.
"I was so shocked when Donald publicly invited Putin to hack into Americans," she told the crowd at Hofstra University. "That is just unacceptable. It's one of the reasons why 50 national security officials who serve in public information has said that Donald is unfit to be the commander in chief."
Trump retorted by saying, "It could be Russia but it could be China. It could be lots of other people. It could be somebody sitting on their bed that weighs 400 pounds, OK? You don't know who broke into the DNC."