After North Korea tested a missile in July 2017, Nikki Haley, then ambassador to the UN, emailed with staff about the launch and sent classified information over an unclassified email system. We obtained the emails: americanoversight.org/document/state… 
This is a real security threat. The State Department's email systems have been hacked before — and Haley and her team discussed a North Korean missile launch using an unclassified system: thedailybeast.com/nikki-haley-us…
Given the attention paid to certain former State Department officials’ emails in 2016, it should be clear to everyone in the Trump administration that classified information should be handled carefully: americanoversight.org/investigation/…
