WASHINGTON — John O. Brennan, the C.I.A. director under President Barack Obama, struck back at President Trump on Thursday for revoking his security clearance, calling the president’s claims of “no collusion” with Russia to influence the 2016 election “hogwash” and arguing that the commander in chief was trying to silence anyone who would dare challenge him.
“Mr. Trump clearly has become more desperate to protect himself and those close to him, which is why he made the politically motivated decision to revoke my security clearance in an attempt to scare into silence others who might dare to challenge him,” Mr. Brennan wrote in an opinion article in The New York Times. He said the move made it more important than ever for Robert S. Mueller III, the special counsel, to complete his investigation of Russia’s election misdeeds without interference from Mr. Trump.
Mr. Trump’s decision to revoke the security clearance drew rebukes Thursday from national security officials and members of both political parties, who called it an extraordinary act of retaliation that reflected authoritarian tactics.
“The fact that the president did this himself leaves him open to the criticism that it looks politically motivated,” Fran Townsend, who served as homeland security adviser in George Bush’s White House, said on CBS. “The notion that you’re going pull somebody’s clearance because you don’t like what they did in government service or you don’t like what they say is deeply disturbing and very offensive.”
In a statement on Wednesday, Mr. Trump cited what he called Mr. Brennan’s “erratic” behavior and “increasingly frenzied commentary,” as grounds for stripping the former intelligence chief of his access to classified information, saying that Mr. Brennan had abused his security clearance “to make a series of unfounded and outrageous allegations.”
Mr. Trump’s decision, announced on Wednesday by Sarah Huckabee Sanders, the press secretary, came only a few weeks after Ms. Sanders warned that Mr. Trump was considering revoking the clearances of Mr. Brennan and others who he believed had politicized and inappropriately profited from their access to delicate information. It was the latest assault by a president who has routinely questioned the loyalties of national security officials and dismissed some of their findings — particularly the conclusion that Moscow intervened in the 2016 election — as attacks against him.
In an interview later in the day with The Wall Street Journal, Mr. Trump drew a direct connection between the investigation and the targeting of Mr. Brennan and others whose security clearances he had said were under review.
“I call it the rigged witch hunt,” Mr. Trump said. “And these people led it!”
“So I think it’s something that had to be done,” he added.
Step by step, from the moment 10 days into his administration that he fired the acting attorney general, Sally Q. Yates, Mr. Trump has overseen the removal of top national security officials who have defied him or worked at senior levels of the Russia investigation. They include James B. Comey, the former F.B.I. director; Andrew G. McCabe, the former F.B.I. deputy director; and Peter Strzok, the former F.B.I. counterintelligence agent who helped oversee the Hillary Clinton email inquiry and the Russia investigation and disparaged Mr. Trump in a series of inflammatory texts.
Mr. Trump’s action against Mr. Brennan appeared to be the first time that a president has ever issued or revoked a clearance outside of the established process, according to Bradley P. Moss, a lawyer who has written on the issue.
In the interview with The Wall Street Journal, Mr. Trump argued that his list of potential targets for having security clearances revoked was not confined to his political opponents, saying that he “would put a Republican on, too, if I thought they were incompetent or crazy.”
The revocation of Mr. Brennan’s security clearance also appeared to be a way to change the subject from damaging accusations in a tell-all book by Omarosa Manigault Newman, a former reality TV show star who worked in the White House and now claims that Mr. Trump used a slur to disparage African-Americans and is in a state of mental decline.
Some Republican lawmakers said they supported Mr. Trump’s decision to move against Mr. Brennan, who has been unusually virulent in his criticism of the president, including accusing him of treason. But it drew criticism across the political spectrum, including from within Mr. Trump’s own party. Senator Bob Corker, Republican of Tennessee and the chairman of the Foreign Relations Committee, said the president’s move was “a banana republic kind of thing” that was inappropriate and vindictive.
A statement from Aitan Goelman, Mr. Strzok’s lawyer, said that Mr. Trump’s move “has taken us down one more step on the path toward authoritarianism.”
The White House statement on Mr. Brennan was dated July 26, three days after Ms. Sanders first announced that Mr. Trump was considering revoking his critics’ clearances. The date suggested that the decision had been made weeks ago, although the White House would not explain the delay in revealing it.
Mr. Trump’s decision to follow through in punishing Mr. Brennan came only a day after his campaign brought an arbitration case against Ms. Manigault Newman to enforce a nondisclosure agreement that she signed in 2016.
Mr. Brennan has become increasingly vocal in his criticism of the president and often tweets or appears on television as a contributor on NBC to question Mr. Trump’s fitness for office. Last month, Mr. Brennan said the president should be impeached for “treasonous” behavior after Mr. Trump stood next to President Vladimir V. Putin of Russia at a news conference in Finland and cast doubt on the conclusion of the intelligence agencies that Moscow interfered in the 2016 presidential election.
On Tuesday, the story of Mr. Trump’s reality star aide turned accuser intersected with that of his frequent public antagonist when Mr. Brennan chastised the president in a tweet for calling Ms. Manigault Newman “that dog.”
Mr. Brennan wrote: “It’s astounding how often you fail to live up to minimum standards of decency, civility, & probity. Seems like you will never understand what it means to be president, nor what it takes to be a good, decent, & honest person. So disheartening, so dangerous for our Nation.”
Ms. Sanders said the president was also considering yanking the security clearances of other former officials and one current Justice Department official, all of whom have angered the president. The group includes Michael V. Hayden, the former head of the National Security Agency who was made C.I.A. director under George W. Bush; Susan Rice, a national security adviser under Mr. Obama; James R. Clapper Jr., the former director of national intelligence under Mr. Obama; and Ms. Yates.
Others who no longer have a clearance might lose the ability to have it reinstated, the president warned. Mr. Comey and Mr. McCabe, neither of whom currently have a security clearance, are part of the list.
The only current official on Mr. Trump’s list is Bruce Ohr, a lawyer in the Justice Department’s criminal division. The president has criticized Mr. Ohr on Twitter because of Mr. Ohr’s friendship with Christopher Steele, a former British intelligence officer who compiled a salacious dossier containing damaging information about the president.
Mr. Ohr’s wife, Nellie — Mr. Trump singled her out as “beautiful” in a tweet over the weekend — worked until September 2016 as a contractor for Fusion GPS, the research firm that commissioned the dossier.
Clearances are typically revoked for cause, because of a security concern like alcoholism, financial problems, health concerns or the mishandling of classified material.
“This is supposed to be an impartial and objective assessment of security concerns,” said Mr. Moss, the lawyer. “This is the president taking a step that he most likely had the legal authority to take, but that no other president has ever thought it proper or justified to do on his own.”
The standard procedure for revoking a security clearance is initiated by the sponsoring agency — which in this case would have been the C.I.A. — and includes memos outlining why a clearance is being withdrawn and, in some cases, an opportunity for the current or former official to offer a defense or rebuttal. The appeals process can be avoided if the head of an agency orders the revocation.
The C.I.A. did not begin a proceeding against Mr. Brennan or take action to remove his clearance, according to officials familiar with the process. The spy agency referred all questions to the White House.
Former high-ranking officials in defense, intelligence, diplomacy and law enforcement usually maintain their clearances when they leave the government, in part to advise those still serving. Keeping such access also increases a former official’s earning potential, helping them land jobs in lobbying, consulting or security contracting or as paid analysts on cable television.
Nearly 4.1 million people have security clearances, according to the most recent report by the Office of the Director of National Intelligence, including 1.3 million with top secret clearances.
Mr. Hayden, in an interview with CNN, said the president had “absolute authority” to oversee security clearances, but that by revoking Mr. Brennan’s for political reasons, Mr. Trump had degraded “the dignity of the office” of the president and suggested he wanted to pressure his critics into silence.
In an email, Mr. Hayden said that losing his clearance would have “a marginal impact on the work I do,” noting, for example, that he would have to resign from the proxy board of an American subsidiary of an Irish company to ensure that its work respects the classification rules of the United States.
Senator Rand Paul, Republican of Kentucky, who first raised the prospect of stripping Mr. Brennan of his clearance in a meeting last month with Mr. Trump at the White House, applauded the president’s action on Wednesday.
“He participated in a shredding of constitutional rights, lied to Congress and has been monetizing and making partisan political use of his clearance since his departure,” Mr. Paul said in a statement.
But Democrats said Mr. Trump’s move against Mr. Brennan was dangerous, likening it to President Richard M. Nixon’s drawing up of a list of political opponents against whom he would use the government to extract revenge.
“An enemies list is ugly, undemocratic and un-American,” Representative Adam B. Schiff of California, the senior Democrat on the Intelligence Committee, said on Twitter. “I also believe this action to silence a critic is unlawful.”