No. Not really. Some 57 days into the presidency of Donald John Trump, however, the precedent is now solid: The President of the United States of America only needs to believe fanciful information he hears, or is told by someone, to publicly state, with no evidence, that what heard or was told is true and to demand investigations the Department of Justice and Congress.
David Graham, writing in Why Trump Can’t Let Go of His Wiretapping Claim for The Atlantic, suggests as his conclusion that:
As long as the White House is going to make Senate committees look into vaguely plausible ideas for which it has no evidence, why not investigate something that many Americans believe in, like UFOs?
Why not indeed. Fox Mulder is happy dancing deep in the sub-antarctic bunker.