WASHINGTON (AP) — Hacking a local election system in the United States wouldn't be easy, and secretly altering votes on a scale massive enough to change the outcome of the presidential race would be impossible, election officials have said, thanks to decentralized systems, paper records for nearly all ballots, exhaustive reviews, legal due process and decades of work by American election officials, volunteers and citizens.

But foreign actors and domestic extremist groups looking to meddle in next week's election can target a much weaker link: voters' perceptions and emotions. Those intent on undermining confidence in U.S. democracy don't have to change any votes if they can convince enough Americans not to trust the outcome.

It's a possible scenario particularly concerning to intelligence analysts and officials tasked with protecting America's election: An adversary tries to hack a state or local election system and then releases a document — perhaps a fake one or even material that is publicly available — and suggests it's evidence of vote rigging.

Or, a video is crafted showing someone supposedly hacking into a ballot scanner, voting machine or a state voter registration system. But it hasn't happened, and it would not be true.

It's called a perception hack, which may or may not include an actual breach of voting systems but is made to appear that has happened. In some cases, minor information might be stolen — enough for a video to appear legitimate — but it does not change votes. A related threat involves fake footage supposedly depicting election workers destroying ballots.

In either case, the goal is the same: to generate confusion, distrust and fear.

Governments at all levels have worked to strengthen election infrastructure in recent years. The human brain, however, remains hard to defend.

"I think that's almost certain to happen," former CIA political analyst Adam Darrah said when discussing the risk of perception hacks.

Darrah, now vice president of intelligence at the cybersecurity company ZeroFox, said misleading people into thinking election systems are vulnerable is a lot easier than actually hacking into them. "It's a way to induce panic. We are very technically resilient. Our emotional resilience, our hypersensitivity, that's still a challenge."

Narrow margins of victory or delays in vote counting could heighten the risk that a perception hack could fool a large number of voters, further polarizing the electorate, raising the risk of political violence and potentially complicating the transfer of power in January.

Intelligence officials warned last week that Russia and Iran may consider encouraging violent protests in the U.S. following the election. The nation's intelligence community and private analysts agree that while the Kremlin is backing former President Donald Trump, Moscow's ultimate goal is to divide Americans and undermine U.S. support for Ukraine and the NATO alliance.

America's adversaries focus on disinformation in part, officials say, because they understand the country's election infrastructure is too secure to hack successfully.

Despite the findings of intelligence officials, both Russia and Iran have rejected claims that they are seeking to influence the U.S. election.

"We have never interfered, we are not interfering, and we do not intend to interfere," a spokesman for the Russian Embassy in Washington wrote in an email to The Associated Press.

Even without a foreign power's involvement, isolated stories of long lines at the polls, ballot mix-ups or other irregularities could be held up as proof that elections can't be trusted.

It happened in 2020, when Trump amplified claims about election problems, helping lead to the Jan. 6, 2021, attack on the U.S. Capitol by his supporters trying to disrupt certification of the election.

The former Republican president has spent months laying the groundwork to challenge the results of this year's election if he loses. And he has worked to convince his supporters that the only way he can lose is if Democrats cheat, urging them to deliver a victory "too big to rig."

"They cheat," Trump said at a Michigan rally last month. "That's the only way we're going to lose, because they cheat. They cheat like hell."

Just as in 2020, the days immediately after the election are likely to be the most critical, as results are announced and Americans come to the end of a contentious race.

It's then that authoritarian nations or domestic anti-democratic groups will look to whip up distrust in an effort to spur people into action, said Paul Barrett, a New York University law professor who studies online discourse and polarization.

"They're happy to see Americans at the throats of other Americans," Barrett said. "We saw that in 2021, and I have tremendous anxiety that we will see a repeat."

In response, national security and election officials across the country have moved to expose disinformation and quickly knock down rumors. Top intelligence officials have held multiple briefings outlining foreign threats, while cybersecurity and election officials have explained why election systems are secure.

Last week, a video purporting to show someone destroying mail ballots in Pennsylvania began spreading on social media. Bipartisan election officials in Bucks County quickly debunked the video, and intelligence officials linked it to a Russian campaign behind other videos seeking to smear Vice President Kamala Harris, the Democratic nominee, and her running mate, Minnesota Gov. Tim Walz.

"That video was debunked pretty quickly on multiple news sites, and I know that Bucks County immediately got out in front of it and basically explained why it was a fake and why voters should have confidence," said Kim Wyman, former secretary of state in Washington state who also has worked at the Cybersecurity and Infrastructure Security Agency.

"But the problem is — now it exists out there," she said. "And we know that it will continue to be circulated between now and probably Inauguration Day."

Americans can help prevent a successful perception hack by not spreading election hoaxes any further. Disinformation experts urge voters to consult a variety of sources of information, be skeptical of anonymous social media claims and turn to their own state and local officials for the facts.

Uncertainty and emotions will be running high in the days after voting ends — exactly the conditions foreign adversaries and domestic extremists need to undermine trust.

"Our foreign adversaries are looking to attack our democratic process to further their own objectives, and we need the help of all Americans in ensuring they are not successful," said CISA senior adviser Cait Conley. "Americans should be confident that their votes will be counted as cast. They should also know that our foreign adversaries will try to make them believe otherwise."

"We encourage everyone to remain vigilant, verify the information they consume, and rely on trusted sources like their state and local election officials," she added.

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Cassidy reported from Atlanta. Associated Press writer Jill Colvin in New York contributed to this report.