Mullin said on July 17 that foreign adversaries can access voting machines and change votes. He said there is no question about the possibility. The comment was made during a news conference on election security held after President Donald Trump addressed the nation. The Department of Homeland Security declined to provide further details when asked, reiterating its call for states to strengthen safeguards against non‑citizen voting. Security experts note that while vulnerabilities in voting machine hardware could allow tampering, no evidence shows that such attacks have been used to affect a U.S. election. J. Alex Halderman, a computer science professor at the University of Michigan, said that hardware attacks could let foreign actors manipulate security controls, but that physical access is required and has not been observed in practice. The Senate Select Committee on Intelligence included similar risk assessments in a 2019 report on Russian interference in the 2016 election, noting that experiments at a security conference demonstrated the ability to hack voting machines when participants had physical access. Election officials typically store machines in locked facilities with video surveillance and restrict access, according to a 2024 National Intelligence Council assessment. Academic analyses from 2006 and 2021 have shown that certain machines can be reprogrammed to alter results without a paper trail, but judges and election officials have said those scenarios are not realistic under current procedures. Andrew Appel, a Princeton University professor emeritus, said modern voting machines are generally more secure than earlier models, and that paper ballots remain the primary method for verification and audit. The absence of confirmed incidents means the claim remains unverified, and ongoing review of voting system security continues.