It now seems the General Flynn was under investigation long before was common knowledge. It would have been impossible for me to know this but, if that was the case, and with me being one of two people who would become president, why was I not told so that I could make a change?— Donald J. Trump (@realDonaldTrump) May 17, 2019
Trump seems to be conflating being warned about Flynn being under investigation with being warned about the Russian threat at all (which he also was warned about, and then claimed he wasn't). But--
Obama warned Trump not to hire Flynn.
Sally Yates warned Trump about Flynn (and got fired).
Trump knew well enough that there was a problem and fired Flynn, but still told Comey to go easy on Flynn (and Comey got fired).
He was warned--he just didn't listen. Or he knew what the situation was, and did not care. Trump is mad at the world on Twitter today because he suddenly cares now.
Seems a bit late, I'm just saying.