Sourcing in that article is extremely thin. Basically it's just quoting Blanche and Trump (hardly neutral observers, the administration is implicated here!) and then citing the existence (but not communication to the journalist) of "officials" who hold the opinion. The CIA thing is hilarious because it says that they aren't convince (I'm not making this up) "according to a source".

This is a beat sweetening story. You write up what your sources want you to write in exchange for them giving you juicier stuff later. It says almost nothing about the certainty within the intelligence agencies.