Matthew Masterson was a senior cybersecurity adviser at CISA, primarily responsible for elections, and his departure comes amid persistent, but baseless, claims that the 2020 elections were riddled with fraud. Many of those have come from President Trump, who last month fired Masterson's former boss, Christopher Krebs, after Krebs joined others in calling the 2020 election the "most secure in American history." Trump's allegations have been widely disputed by election experts and numerous courts, where his campaign has tried unsuccessfully to overturn the election results.