State Department officials determined that Iran hacked their emails and social media accounts during a particularly sensitive week for the nuclear deal in the fall of 2015, according to multiple sources familiar with the details of the cyber attack.
The attack took place within days of the deal overcoming opposition in Congress in late September that year. That same week, Iranian officials and negotiators for the United States and other world powers were beginning the process of hashing out a series of agreements allowing Tehran to meet previously determined implementation deadlines.
Critics regard these agreements as "secret side deals" and "loopholes" initially disclosed only to Congress.
Sources familiar with the details of the attack said it sent shockwaves through the State Department and the private-contractor community working on Iran-related issues.
It is unclear whether top officials at the State Department negotiating the Iran deal knew about the hack or if their personal or professional email accounts were compromised.