According to records released as a result of a Freedom of Information Act lawsuit filed by Judicial Watch, State Department technicians shut off the security features on Hillary Clinton’s private server in 2010, leaving it at higher risk for hacker intrusion. Emails from December of that year show that IT staffers disabled a piece of Trend Micro security software on Clinton’s server because it was conflicting with the email delivery system. It remained disabled for an unknown length of time.

The server’s increased vulnerability isn’t just a matter of theory; only a few weeks after the software was disabled, we know that hackers breached the server. Emails from that time show that Clinton’s aides were advised not to send her any sensitive messages due to a possibly leak in the system. When, how, or even if these breaches were repaired remains unclear, just as its unclear whether or not hackers gained access to any of Clinton’s emails.

But the mere fact that the possibility exists – a possibility that could have easily been avoided or at least mitigated by established protocols – is enough to cast deep concerns on a Hillary Clinton presidency. As Donald Trump said in a speech this week, the dangers aren’t limited to Top Secret classified files.

Foreign governments, he said, “probably now have a blackmail file over someone who wants to be the President of the United States. This fact alone disqualifies her from the presidency. We can’t hand our government to someone whose deepest, darkest secrets may be in the hands of our enemies.”

Hopefully, this will be a point that Trump comes back to again and again throughout the campaign. Because he’s absolutely right. Hillary Clinton deleted thousands of personal emails off that server because she was so terrified that someone in the public might get a peek. Now that’s fine…few of us would want our personal emails published in the New York Times. But if she doesn’t want them out there and someone in North Korea has them…well, that gives them a lot of power, don’t you think?

Hillary Clinton’s email server proves she’s arrogant, incompetent, and deceitful, but it also makes her a dangerous liability for the United States.