President Donald Trump's latest tweet storm Friday renewed echoes of Watergate and raised new legal questions about Trump's firing of James Comey earlier this week.

“James Comey better hope that there are no 'tapes' of our conversations before he starts leaking to the press!” Trump tweeted at 8:26 a.m. Eastern Daylight Time.

That comment alone could constitute obstruction of justice, Harvard Law School professor Laurence Tribe told The National Law Journal Friday. “That threat … is certainly pointed enough in the context of everything else we know including Trump's own account of the dinner with Comey, to be part of a pattern of obstruction of justice.”