Sorry, WaPo. We don’t believe a word you publish anymore. You SAY you’ve obtained a memo, well you’re going to have to publish a photo of said memo to prove:
1. you even have a memo,
2. the memo isn’t a fake,
3. who in the Pentagon signed the memo, and
4. what exactly the memo said, e.g., any reason given, etc.
Even then it’d be much more Occam’s Razorish to simply assume WaPo created the memo themselves.