Journalist Seymour Hersh wrote that "Flynn confirmed [to Hersh] that his agency had sent a constant stream of classified warnings … about the dire consequences of toppling [Syrian President] Assad." Flynn recounted that his agency was producing intelligence reports indicating that radical Islamists were the main force in the Syrian insurgency and "that Turkey was looking the other way when it came to the growth of the Islamic State inside Syria". According to Flynn, these reports "got enormous pushback from the Obama administration," who he felt "did not want to hear the truth".
https://en.wikipedia.org/wiki/Michael_Flynn
Seymour Hersh has regularly exposed the false flag chemical attacks in Syria.
https://www.zerohedge.com/news/2017-06-26/seymour-hersh-us-lied-about-syrian-chemical-attack-then-bombed-them-anyway
Flynn had probably been leaking to Hersh that the chemical attacks were fake since 2013.
Flynn has been going against the deep state's plans in the middle east for at least 5 years if not more. He knows exactly what he was doing when he plead "guilty" to lying.
He plead guilty to make a deal.