In a continuation of Signalgate, Hegsgeth came under scrutiny again last month, when the Washington Post reported that he not only had Signal installed on his phone, but that he also used a so-called unsecured internet line to bypass Pentagon security and install Signal on a desktop computer.

President Donald Trump has gone through his share of national security advisers. But he doesn't hold the record, yet.

National security adviser Mike Waltz is leaving his White House post, although soon after reports about his departure were published, President Trump announced he plans to nominate him to be ambassador to the United Nations.