The New York Times first reported that Walsh, an Iraq war veteran and graduate of the United States Army War College, appears to have lifted the recommendations in his thesis almost word for word from a Carnegie Endowment for International Peace report without attribution.
The senator later told the Associated Press that he had been dealing with PTSD from his service in Iraq and taking medication to treat nightmares, anxiety and sleeplessness. He said that he also had been stressed by a fellow veteran's suicide at the time he was writing the paper.
"I don't want to blame my mistake on PTSD, but I do want to say it may have been a factor," Walsh said, as quoted by the AP. "My head was not in a place very conducive to a classroom and an academic environment."
Walsh told the AP that he has since worked through those issues, although he still takes antidepressant medication.