I don’t have a link but my understanding is that Flynn and Obama had a policy difference of opinion related to terrorism and that was the basis for the ‘warning’. They have smeared Flynn as a shady character that Trump should have avoided.
Truth. And that was always the way with Obama. Anyone who got in the way of Democrat power was tyrannically and lawlessly retaliated against and silenced.
WHY LT. GENERAL MICHAEL FLYNN MATTERS THE MOST TO TRUMP
As is well documented, General Flynn publicly disagreed with the Obama White House, urging a comprehensive rethink of our military strategy. That was rejected, and he was fired by Obama.