WASHINGTON – Justice Department lawyers had signed off and the president of the United States had issued his orders.

So less than a month after the Sept. 11, 2001, terrorist attacks, Air Force Gen. Michael Hayden decided to carry out a covert warrantless eavesdropping program to help thwart future attacks.

“The math was pretty straightforward,” Hayden told the Senate Intelligence Committee on Thursday at his confirmation hearing to head the Central Intelligence Agency. “I could not not do this.”

Hayden, who headed the National Security Agency when it began the eavesdropping program, defended the Bush administration’s effort to wiretap calls between suspected al-Qaida allies and U.S. residents, saying the practice is subject to strict internal reviews to prevent civil rights violations.

Hayden seems assured of Senate confirmation to take over the CIA and would become the agency’s third director since the Sept. 11 attacks. The committee will vote next week. President Bush has pressed for a full Senate vote before the Memorial Day recess begins at the end of next week, but that’s uncertain.

Even so, Hayden faced tough questions about his credibility, the breadth of the eavesdropping program, the role of the CIA in the treatment of foreign detainees, and the reliability of intelligence on Iran’s nuclear program. On key points, Hayden demurred, putting off his answers for the classified, closed-door portion of the hearing.

Indeed, the more than six-hour public session revealed more about the frustrations of lawmakers who’d been kept in the dark about the NSA’s activities – some until Wednesday – than it did about Hayden’s views.

“The Congress was really never really consulted or informed in a manner that we could truly perform our oversight role as co-equal branches of government, not to mention, I happen to believe, [as] required by law,” said Sen. Olympia Snowe, R-Maine.

Hayden promised to keep senators informed about intelligence activities, but he urged lawmakers to stop the “endless picking apart of the archaeology of every past intelligence success or failure.”

CIA officers, he said, “deserve not to have every action analyzed, second-guessed and criticized on the front pages of the morning paper.”

As for the NSA’s eavesdropping activities, Hayden stressed that the program targets al-Qaida communications. In one of the most detailed descriptions that the administration has offered about internal safeguards on the program, Hayden said that NSA officers listen in on calls only after establishing probable cause that the calls involve al-Qaida suspects. He said each targeted call is documented and includes a detailed rationale for linking a phone number with a suspected terrorist.

He said the NSA’s inspector general, the agency’s internal watchdog, and Department of Justice lawyers routinely examine the targeting documents to make sure the program isn’t being abused.

“To the best of my knowledge, the folks out there are batting a thousand,” he said. “No one has said that there has been a targeting decision made that wasn’t well-founded in a probable cause standard.”

He declined to describe the breadth of the program. He also wouldn’t confirm a USA Today report last week that the NSA had access to a database of millions of records of phone calls placed in the United States.

After Sen. Carl Levin, D-Mich., sparred with Hayden over the privacy issues associated with warrantless wiretaps, Levin asked: “Is that the whole program?”

“Senator, I’m not at liberty to talk about that in open session,” Hayden replied.

Later, Levin told a reporter: “He’s made generally a positive impression on me.”

While the revelations of NSA eavesdropping have caused an outcry among civil libertarians and a vigorous debate in Congress, the Senate hearing was a civil encounter. Administration critics sat quietly in the audience, clapping softly at the occasional pointed question from a senator.

Sen. Chuck Hagel, R-Neb., encouraged Hayden to develop a new sense of public trust in the intelligence community.

“America has lost confidence in the leadership of this country,” Hagel said.

Hayden conceded flaws in the intelligence gathering about weapons of mass destruction in Iraq. He faulted the Pentagon’s former Office of Special Plans, headed by former Undersecretary of Defense of Policy Douglas Feith, for not adequately filtering intelligence data when reaching conclusions about weapons of mass destruction in Iraq and about links between Iraqi dictator Saddam Hussein and al-Qaida.

Displaying a gift for metaphor, Hayden said:

“I’ve got three great kids, but if you tell me, ‘Go out and find all the bad things they’ve done, Hayden,’ I can build you a pretty good dossier, and you’d think they were pretty bad people because that was what I was looking for and that’s what I’d build up.

“That would be very wrong. That would be inaccurate. That would be misleading.”

Asked to compare current assessments about Iran’s nuclear capabilities with prewar intelligence about Iraq, Hayden said, “Our data is better … and our judgments are far more clear.”

At another point he noted: “Iran is a difficult problem.”