For years (decades; maybe even centuries), administrations have used leaks from “unidentified sources” as a way to test out ideas, send signals or warnings, etc., both to the public and to other governments. The leak gets the idea out, without requiring a detailed explanation from the administration. It’s vague and inherently imprecise. And the idea or leak can be abandoned, if necessary, without affecting the administration’s credibility.
All of which, with the exception of the last point above, sounds like Donald Trump’s tweets. Consider President Trump’s tweet of a week ago:
“Why would I call China a currency manipulator when they are working with us on the North Korean problem?”