On October 4, 2017, Luis Elizondo resigned from the Pentagon after 22 years of government service, sending a letter to the Secretary of Defense protesting what he described as excessive secrecy and internal resistance to briefing senior DoD leadership on AATIP findings.

Elizondo stated that he wrote his resignation letter to compel the Secretary of Defense to address UAP: 'I wrote in my resignation letter what I thought the boss needed to hear, and that was that these things are real.' He subsequently joined To The Stars Academy of Arts and Science, co-founded by musician Tom DeLonge, and worked with journalists to publish classified UAP footage.