In early-morning tweets Tuesday, President Donald Trump criticized the raid on his lawyer Michael Cohen.

He said "Attorney-client privilege is dead!" and called the special-counsel investigation "A TOTAL WITCH HUNT!!!"

It is unclear exactly what prompted the raid, but the standards for obtaining such a warrant would have been high.

President Donald Trump declared attorney-client privilege "dead" on Tuesday, the morning after the FBI raided the offices of his lawyer Michael Cohen.

In two early-morning tweets, Trump called the raid "A TOTAL WITCH HUNT!!!" He had made the same assessment to reporters on Monday evening after news emerged that the raid had taken place that morning.

He also tweeted "Attorney-client privilege is dead!"

Communications between clients and their lawyers are often beyond the reach of law enforcement based on attorney-client privilege, derived from the US Constitution.

But when the occasion warrants it, authorities have the ability to waive this provision.

Business Insider on Monday reported that such a raid would have a high burden for approval, with authorities needing to convince a judge that less intrusive measures had no chance of success. The exact reason for the raid was unclear, but reports Monday indicated that the matter was referred to the FBI by Robert Mueller, the special counsel leading the Russia investigation.

A former federal prosecutor, Ken White, in a blog for Reason, wrote: "That's a very fraught and extraordinary move that requires multiple levels of authorization within the Department of Justice" and an "elaborate review process."

The FBI collected records related to several topics, including Cohen's $130,000 payment to the adult-film star Stormy Daniels just before the 2016 presidential election, The New York Times reported Monday.

"I have this witch hunt constantly going on," Trump told reported Monday at an event inside the White House, calling the raid "an attack on our country" and on "what we all stand for."

Trump also called Cohen a "good man" and labeled Mueller's team "the most conflicted group of people I have ever seen."