President Donald Trump insisted Saturday that his former national security adviser Michael Flynn had done nothing illegal during the transition.

Flynn pleaded guilty Friday to lying to the FBI about contacts he had with the Russian ambassador. Trump said he fired Flynn because he lied to the vice president and the FBI about those dealings.

"It is a shame because his actions during the transition were lawful. There was nothing to hide!" Trump said in a tweet, his second comment of the day of the explosive turn of events in the Russia probe.