The cybersecurity chief for Democratic candidate for president Pete Buttigieg’s campaign has resigned, amid warnings from intelligence officials and cybersecurity experts that presidential campaigns face challenges in thwarting cyberattacks and disinformation campaigns.

Mick Baccio left his job as chief information security officer for Mr. Buttigieg’s campaign earlier this month due to differences with campaign leadership over how to manage information security, said a person familiar with the matter.

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