After reports of alleged Russian hacking into Democratic Party computer networks, some commentators have suggested that the Russians could hack the results of the U.S. elections. Other analysts have, well before this year’s campaign, suggested that election results in the U.S. could be electronically manipulated, including by our fellow Americans. So could an American election’s outcome be altered by a malicious actor on a computer keyboard? I have had three jobs that, together, taught me at least one thing: If it’s a computer, it can be hacked. For Presidents Bill Clinton and George W. Bush, I served as the White House senior cybersecurity policy adviser. For President Barack Obama, I served on his five-person post–Edward Snowden investigative group on the National Security Agency, intelligence and technology. And for over a decade I have advised American corporations on cybersecurity. Those experiences confirm my belief that if sophisticated hackers want to get into any computer or electronic device, even one that is not connected to the internet, they can do so. The U.S., according to media reports, hacked in to the Iranian nuclear centrifuge control system even though the entire system was air-gapped from the internet. The Russians, according to authoritative accounts, hacked into the Pentagon’s SIPRNet, a secret-level system separate from the internet. North Koreans, computer forensics experts have told me, penetrated SWIFT, the international banking exchange system. Iranians allegedly wiped clean all software on over 30,000 devices in the Aramco oil company. The White House, the State Department and your local fast food joint have all been hacked. Need I go on?