US President Donald Trump on Saturday again exploded on Twitter and took another swipe at the former President Barack Obama, accusing him of being “a bad, (or sick) guy who wire-tapped his phones before the election.

“Terrible! Just found out that Obama had my ‘wires tapped’ in Trump Tower just before the victory. Nothing found. This is McCarthyism!,” he wrote.

“Is it legal for a sitting President to be ‘wire-tapping’ a race for president prior to an election? Turned down by court earlier. A NEW LOW!” he added

It wasn’t clear what, exactly, Trump was referring to as he accused his predecessor, whom he labeled a bad (or sick) guy!” He also said a talented lawyer could make “a great case” out of the situation.

Obama’s post-presidency office did not immediately respond to a request for comment from Yahoo News on Trump’s accusation, and the White House did not immediately clarify from whom Trump had “just learned” this new information.

Trump has the authority to declassify almost any classified material, and could substantiate his accusations if he wanted to. The Saturday-morning Twitter storm was striking as Trump and Obama had largely appeared to paper over their differences — at least publicly — since the election.