WASHINGTON -- In a tumultuous start to the confirmation hearing for John O. Brennan as director of the Central Intelligence Agency on Thursday, protesters briefly disrupted his testimony and Mr. Brennan came under unexpectedly intense questioning from both Democrats and Republicans about drone strikes, leaks of classified information and his knowledge of the agency's former interrogation program.
Amid widespread controversy over the Obama administration's use of targeted killings by drones, the chairwoman of the Senate Intelligence Committee, Dianne Feinstein, Democrat of California, said she would review proposals to create a new court to oversee such strikes. She gave no details but said it would be analogous to the Foreign Intelligence Surveillance Court, which oversees eavesdropping on American soil.
Before the hearing began, a group of protesters stood up and began shouting at Mr. Brennan before they were escorted out of the hearing room. One man yelled, "Assassination is against the Constitution!" and one woman held up a sign that read "Drones Fly Children Die."
But the protests continued as Mr. Brennan began his opening statement. After the fifth interruption, Ms. Feinstein temporarily stopped the hearing and cleared the room, asking that activists from the peace group Code Pink not be readmitted.
When Mr. Brennan resumed his testimony, the top Republican on the committee, Senator Saxby Chambliss of Georgia, pressed him on his knowledge of the C.I.A.'s use of brutal interrogation methods under President George W. Bush. Mr. Brennan was deputy to the agency's No. 3 officials when the coercive interrogations were first used but said he had no involvement in the program.
Mr. Chambliss sounded skeptical, saying records showed Mr. Brennan had received 50 e-mails about the interrogation of Abu Zubaydah, a terrorist facilitator caught in Pakistan in 2002 and subjected to waterboarding, the near drowning technique used by C.I.A. interrogators.
Pressed on conflicting accounts of the interrogation program, Mr. Brennan declared, "At this point, Senator, I do not know what the truth is."
Mr. Brennan on several occasions declined to describe waterboarding interrogations as "torture." He instead called them "reprehensible" and "something that should not be done." Leon E. Panetta, who served as President Obama's first C.I.A. director, was unequivocal during his confirmation hearing in referring to waterboarding as torture.
Senator Jim Risch, Republican of Idaho, accused Mr. Brennan of having improperly disclosed information to television commentators about a foiled terrorist plot in Yemen to bomb a United States-bound airliner. Mr. Brennan admitted that he told the commentators that the United States had "inside control" of the operation, but denied the suggestion that he had exposed the fact that a double agent for Western intelligence was inside the Qaeda branch in Yemen. The F.B.I. is currently investigating the source of that leak.
"It seems to me that the leak the Department of Justice is looking for is right here in front of us," Mr. Risch said. Mr. Brennan strenuously disagreed, saying he was a witness and not a target of the investigation.
In his opening statement, Mr. Brennan acknowledged "widespread debate" about the administration's counterterrorism efforts.
But he said that the United States remained "at war with Al Qaeda and its associated forces," which "still seek to carry out deadly strikes against our homeland and our citizens."
He later testified that when C.I.A. drone strikes accidentally kill civilians, those mistakes should be made public. "We need to acknowledge it publicly," he said.
The hearing came days after the leak of a Justice Department document explaining the legal rationale for the killing of Anwar al-Awlaki, an American citizen who had joined Al Qaeda in the Arabian Peninsula and was killed in Yemen in September 2011. Mr. Brennan, a former C.I.A. station chief in Saudi Arabia, has been central to the Obama administration's clandestine war inside Yemen.
Pressured by members of Congress in the days before the hearing, the White House on Wednesday ordered the Justice Department to provide the Congressional Intelligence Committees with the formal, classified memos that provide the legal justification for the killing of Mr. Awlaki and other American citizens overseas who are considered terrorists. The Obama administration had previously refused to give lawmakers the full memos, written by the Justice Department's Office of Legal Counsel.
If he returns to the C.I.A. as its director, Mr. Brennan will inherit an agency that has changed drastically in the years since the attacks of Sept. 11, 2001, with a new focus on hunting down terrorists that has led some to say that the agency has strayed too far from its traditional mission of foreign espionage and analysis.
In his responses to questions posed by the Senate Intelligence Committee in advance of the hearing, Mr. Brennan hinted that he shared some of these concerns. For instance, he said that the agency's performance in anticipating and analyzing the tumult in the Arab world since 2011 shows "that the C.I.A. needs to improve its capabilities and its performance still further."
Mr. Brennan, 57, was first exposed to the Middle East while he was a student at Fordham University and spent a year abroad at the American University of Cairo studying Arabic. His 1980 master's thesis at the University of Texas was called "Human Rights: A Case Study of Egypt." That year, after spotting a newspaper ad recruiting for the C.I.A., he joined the agency.
He served as a Middle East analyst, as a briefer for President Bill Clinton and as station chief in Saudi Arabia from 1996 to 1999, forming relationships with Saudi officials whom he would later consult constantly about Yemen. By the end of the 1990s, he was serving as chief of staff to the director, George J. Tenet, and when terrorists struck in 2001 he was deputy to the agency's third-ranking official.
He was in charge of the creation of the agency now called the National Counterterrorism Center, founded at the urging of the national commission on the Sept. 11, 2001, terrorist attacks. He left the government in 2005 for a lucrative job running an intelligence contracting firm, the Analysis Corporation, that worked closely with his government security agencies.
Mr. Brennan was an early supporter of Mr. Obama in 2008, though the men did not meet until after the election. Though he was a leading candidate for C.I.A. director, he withdrew from consideration for the post, citing what he considered to be unfair criticism from human rights advocates for his role as a senior agency official when it was using brutal interrogation methods.
In a statement released on Wednesday, the American Civil Liberties Union urged the Senate to demand more details from Mr. Brennan about both the interrogation and targeted killing programs.
"Brennan has been something of a Forrest Gump of toxic national security policies, having been in the room when everything from torture to the killing of an American citizen was being debated," wrote Christopher Anders, the A.C.L.U.'s senior legislative counsel.
Given his wide-ranging portfolio of the past four years, Mr. Brennan's move to the C.I.A. would narrow his responsibilities. He would have a role in the debate about whether the agency should gradually shift drone operations to the Defense Department, as many experts advise.
Mr. Panetta, who headed the C.I.A. from 2009 to 2011 and has served as defense secretary since then, told NBC News on Sunday that he favored shifting most strikes to the military. "The advantage to it is it becomes much more transparent," Mr. Panetta said.
Mr. Brennan would have to impose on the agency a new, formal set of rules for targeted killing that he himself helped write in recent months. Both C.I.A. and Pentagon counterterrorism officials have pressed for greater freedom to hit militant suspects, and colleagues say Mr. Brennan has often been a restraining voice in the debate.
How his influence on strikes might shift were he to be confirmed and take over at C.I.A. headquarters is uncertain.
"If confirmed," he told the Senate panel in the written questions, "I would not be the director of a C.I.A. that carries out missions that should be carried out by the U.S. military."
This article originally appeared in The New York Times.