The threat of computer hacking and the potential for violent clashes is darkening an already rancorous presidential race between Democrat Hillary Clinton and Republican Donald Trump, amid fears that Russia or other actors could spread political misinformation online or perhaps tamper with voting.

To counter the cyber threat, all but two U.S. states have accepted help from the U.S. Department of Homeland Security (DHS) to probe and scan voter registration and election systems for vulnerabilities, a department official told Reuters.

Ohio has asked a cyber protection unit of the National Guard, a reserve force within the U.S. military, for assistance to protect the state’s systems.

On Thursday, Arizona Secretary of State Michele Reagan and her cyber security team met with officials from the Federal Bureau of Investigation (FBI) and the DHS, in addition to state-level agencies, to discuss cyber threats, said Matt Roberts, a spokesman for Reagan.

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Cyber security experts and U.S. officials say chances that a hack could alter election outcomes are remote, in part because voting machines are typically not connected to the Internet.

But the FBI sent a flash alert in August to states after detecting breaches in voter registration databases in Arizona and Illinois.

Armed Groups

Unidentified intelligence officials told NBC News on Thursday that there is no specific warning about an Election Day attack, but they remain concerned that hackers from Russia or elsewhere may try to disrupt the process, likely by spreading misinformation by manipulating social media sites such as Facebook and Twitter.

DHS cyber security experts plan to hold a media briefing on Friday to discuss the agency’s efforts with states to boost the security of their voting and election systems.

The potential for violence around the election has loomed in the background of the campaign for months. Armed groups around the country have pledged in unprecedented numbers to monitor voting sites for signs of election fraud.

Voter intimidation reported at polling sites so far prompted Democrats to accuse Trump of a “campaign of vigilante voter intimidation” in four states on Monday.

But local authorities surveyed by Reuters on Thursday in five states—Ohio, Pennsylvania, Arizona, Wisconsin and Florida—said they were not increasing election-related law enforcement personnel or resources above 2012 levels.

‘A Lot of Talk, Little Action’

The FBI, which designates one special agent from each of its 56 field offices for election crime matters, has not increased its numbers or given staff additional training this year, said an FBI spokeswoman.

There has been no “substantive change” in the number of personnel deployed by the rest of the Justice Department, which designates Assistant U.S. Attorneys and federal prosecutors within the agency’s Public Integrity Section to handle election crimes, according to a spokesman.

Jim Pasco, executive director of the Fraternal Order of Police, which represents hundreds of thousands of U.S. officers, said cops are taking the same security measures they would take for any large event. He said he expects the vows by militias to monitor the polls to be “a lot of talk, little action.”

Civil rights groups said deploying more police officers to the polls can actually intimidate voters.

“The presence of law enforcement can have a chilling effect on the electorate,” said Kristen Clarke, president of the Lawyers’ Committee for Civil Rights Under Law, a watchdog group. “That’s something we want to discourage.”