@evan So far as I can tell (I've been away), it was entirely done using Twitter: no speech, no press conference, no advance notice to his aides. Looking at https://www.whitehouse.gov/briefing-room/ , I don't even see a press release.
Putting aside any issues one might have with Twitter, this is not how to manage an important matter. I've seen people joke that this was a coup by the intern who manages Pres. Biden's social media account. I don't see how to prove it wasn't.