WASHINGTON - CIA Director John Brennan, responding to the Senate torture report, acknowledged yesterday in a rare televised news conference that "abhorrent" tactics were used on terror detainees and said it was "unknown and unknowable" whether the harsh treatment yielded crucial intelligence that could have been gained in any other way.

Brennan began his public explanation - a rarity for his by-nature secretive agency - recounting the horrors of the 9/11 terrorist attacks, his agency's determination to prevent more such assaults and the fact that CIA officers were the first to fight and early to die in the Afghanistan war. The CIA, he said, "did a lot of things right" in a time when there were "no easy answers."

Brennan criticized the Senate intelligence committee's investigation on multiple fronts, saying, for example, it was "lamentable" that the committee interviewed no CIA personnel to ask "what were you thinking" and "what was the calculus you used" in determining interrogation practices. Without that, he said, "you lose the opportunity to really understand what was taking place at the time."

Even so, on the central contentious point of this week's report - its conclusion that none of the torture or other brutal interrogation methods produced critical, life-saving intelligence - Brennan said that cannot be proved one way or the other. In that respect, he stopped short of the claims of other defenders of the program who said the tough methods saved thousands of American lives and provided the breakthrough in finding Osama bin Laden.

Valuable information was indeed obtained after the harsh interrogations, he said, including some on 9/11 mastermind Osama bin Laden. But he added it was impossible to know whether the detainees provided that information because of the "enhanced interrogation techniques." He said the cause-and-effect relationship is "unknown and unknowable."

Brennan refused to say whether he considered the techniques to be torture, declining to even use the word in his 40 minutes of remarks and answers to questions.

As he spelled out his objections to the report, the office of Democratic Sen. Dianne Feinstein, head of the Senate intelligence committee, unleashed a barrage of tweets challenging him. One said that "every fact" in the committee's report was based on CIA records, cables or other evidence.

Brennan denied that the CIA intentionally misled lawmakers, and he spoke up forcefully for agency employees, "a workforce that was trying to do the right thing" even though some came up short.

"We take exceptional pride in providing truth to power," he said pointedly, "whether that power agrees with what we say or not and regardless of political party."

The Senate report doesn't urge prosecution for wrongdoing, and the Justice Department has no interest in reopening a criminal probe.