President Donald Trump has called the federal raid on the offices of his personal lawyer "a disgrace".
On Monday, federal agents searched the office of Michael Cohen, seizing records on topics including a $130,000 (€105,600) payment made to a porn actress who says she had sex with Mr Trump more than a decade ago.
The move ignited the president's anger, with Mr Trump calling it a "disgrace" that federal agents "broke into" the office of his personal lawyer. He also called special counsel Robert Mueller's investigation "an attack on our country".
Mr Trump called the probe a "witch hunt," suggesting it was a distraction from serious issues, such as the consideration of a military response to Syria's apparent use of a chemical weapon on civilians over the weekend - which was a subject of his Monday evening meeting with the defence secretary, the joint chiefs of staff and US combatant commanders.
Instead, Mr Trump opened with an unprompted four-minute critique of Mr Mueller's investigation. "I just heard that they broke into the office of one of my personal attorneys, a good man," Mr Trump began, referring to the agents who had obtained search warrants from a federal judge.
The raid on Mr Cohen's office was done by the US Attorney's office in Manhattan and was based at least partly on a referral from Mr Mueller, according to Mr Cohen's lawyer, Stephen Ryan.
"The decision by the US Attorney's Office in New York to conduct their investigation using search warrants is completely inappropriate and unnecessary," Mr Ryan said in a statement.
"It resulted in the unnecessary seizure of protected attorney client communications between a lawyer and his clients."
The raid creates a new legal headache for Mr Trump even as he and his lawyers weigh whether to agree to an interview with Mr Mueller's team, which in addition to investigating potential ties between Russia and the Trump campaign is also examining whether the president's actions constitute obstruction of justice.
The law enforcement action will almost certainly amplify the public scrutiny on the payment to the actress, Stormy Daniels, which was made just days before the 2016 presidential election.
Mr Trump told reporters last week that he did not know about the payment.
Still, the existence of a referral from Mr Mueller's office to the Manhattan US Attorney suggests that the matter is not related to Russia.
Under Justice Department regulations, Mr Mueller is required to consult with Deputy Attorney General Rod Rosenstein when his investigators uncover new evidence that may fall outside his original mandate.
Mr Rosenstein then will determine whether to allow Mr Mueller to proceed or to assign the matter to another US lawyer or another part of the Justice Department.
A spokesman for Mr Mueller's office did not immediately return a call seeking comment.
White House spokeswoman Sarah Huckabee Sanders and the US Attorney's office also had no comment. The New York Times first reported on Monday's raid.
Mr Ryan did not elaborate on the documents that were taken from Cohen's office but said he has cooperated with investigators, including meeting last summer with politicians looking into Russian interference in the 2016 presidential election.
Mr Cohen has more recently attracted attention for his acknowledgement that he paid ms Daniels $130,000 out of his own pocket just days before the 2016 presidential election.
Mr Cohen has said neither the Trump Organisation nor the Trump campaign was a party to the transaction with Ms Daniels and he was not reimbursed for the payment.
Several former officials at the Federal Election Commission (FEC) have said the payment appears to be a violation of campaign finance laws, and multiple Washington-based groups have filed complaints with the FEC, urging it to investigate.
There have been few signs that Mr Mueller was interested in investigating the payment, though. One Mueller witness, former Trump aide Sam Nunberg, recently connected the special counsel with the payment, saying in an interview on MSNBC last month that prosecutors had asked him about it.
Mr Trump answered questions about Ms Daniels for the first time last week, saying he had no knowledge of the payment made by Mr Cohen and he did not know where Mr Cohen had got the money. The White House has consistently said Mr Trump denies the affair.
Ms Daniels has said she had sex with the president in 2006. She has been suing to invalidate the nondisclosure agreement she signed before the election and has offered to return the £130,000 she was paid in order to "set the record straight".
Ms Daniels argues the agreement is legally invalid because it was signed by only Ms Daniels and Mr Cohen, and was not signed by Mr Trump.
Last month, Ms Daniels' lawyer, Michael Avenatti, sent letters to the Trump Organisation demanding the business preserve all of its records relating to the $130,000 transaction.
The letter demanded they preserve all emails by Mr Cohen that mention Ms Daniels, whose real name is Stephanie Clifford, as well as any emails and text messages related to the alleged relationship. He sent similar demand letters to two banks - City National and First Republic - asking they preserve documents connected to the transaction.
Mr Avenatti also enclosed an email showing Mr Cohen had used his Trump Organisation email address in correspondence with a representative from First Republic. In the email, the representative said funds had been deposited in Mr Cohen's account.
Federal agents searched Mr Cohen's office at 30 Rockefeller Plaza in New York, where he had been working as part of a "strategic partnership" with the law firm Squire Patton Boggs.
On Monday, the firm said in a statement that its relationship with Mr Cohen had "reached its conclusion, mutually and in accordance with the terms of the agreement".
"We have been in contact with Federal authorities regarding their execution of a warrant relating to Mr Cohen," the firm's statement said. "These activities do not relate to the firm and we are in full cooperation."