Washington (CNN) -- The Rolling Stone magazine journalist whose article about Gen. Stanley McChrystal helped end the Afghanistan commander's career has been denied permission to embed with a military unit in Afghanistan, a Pentagon spokesman told CNN Wednesday.
"Embeds are a privilege, not a right. The unit decided they didn't feel the trust necessary for an embed. They declined," Pentagon spokesman Col. David Lapan said, not specifying which unit was involved.
Michael Hastings, the reporter, said via Twitter that his embed had earlier been approved, then was "disapproved."
McChrystal's illustrious career came to an abrupt end when he resigned after he and his staff were quoted in a Hastings article criticizing and mocking key Obama administration officials.
The Army is investigating the circumstances that led to the article, an Army spokesman told CNN Wednesday.
"A four-star commander was relieved ultimately due to this article. We want to understand what happened here," Col. Tom Collins said.
The Army Inspector General, the service's independent investigative arm, began the investigation shortly after President Barack Obama fired the general in June, Collins said Wednesday.
He declined to answer questions about the scope of the review or who was being interviewed, because the investigation is ongoing.
