CIA Director John O. Brennan maintained his objections about a Senate Intelligence Committee report on the agency’s post-9/11 interrogation program during a rare news conference Thursday, saying the use of enhanced techniques produced useful intelligence while adding it is impossible to know if that was because of those techniques.

“The cause and effect relationship between the use of EITs and useful information subsequently provided by the detainees is in my view unknowable,” Brennan said.

Brennan also said he was troubled by the study’s findings that the CIA for years misled the Congress, the White House and the public about the brutality of interrogation techniques, their effectiveness and how often they were used.

“The study’s contention that we repeatedly and intentionally misled the public and the rest of the U.S. government rests on the committee’s view that detainees subjected to EITs did not produce useful intelligence, a point on which we still fundamentally disagree.”