If only someone who wasn't former President Barack Obama had raised some red flags about Michael Flynn.

On Friday, President Trump dug up an old complaint about his quickly disgraced national security adviser, tweeting that "it now seems the General Flynn was under investigation long before was common knowledge" and questioning why he wasn't told about it. Except it's public knowledge that Obama fired Flynn, and that he warned Trump against bringing him back on.

Trump's tweet disregards a two-year-old NBC News report that said Obama told Trump not to hire Flynn "less than 48 hours" after Trump won the presidency. Former White House Press Secretary Sean Spicer later admitted that Trump knew Obama "wasn't exactly a fan" of Flynn.

Trump hired and quickly fired Flynn as national security adviser in the early days of his presidency. Flynn later pleaded guilty to lying to the FBI, and eventually gave interviews to Special Counsel Robert Mueller. Trump's tweet is likely tied to the Thursday revelation that Flynn told investigators that people with ties to the Trump administration and Congress contacted him in an attempt to interfere with the Russia probe. Mueller included that information in newly unredacted court papers.