WASHINGTON (AP) -- The festering dispute between the CIA and U.S. Senate investigators that exploded in public this week shows just how hard it can be to learn from the past and move on.
More than 12 years after the Sept. 11 attacks, the government still is struggling with what kind of public reckoning is due for harsh interrogation techniques introduced by President George W. Bush and banned by his successor, President Barack Obama.
Some questions and answers about how the Senate and the CIA got here and what happens next:
Q: What are the CIA and the senators quarreling about?
A: The CIA likes to hold its secrets close. It's the job of the Senate Intelligence Committee, along with its House counterpart, to keep tabs on the spy agency. Those interests have collided during the Senate committee's exhaustive review of the CIA's detention and interrogation program. Since 2009, the committee has worked on a classified report about waterboarding and other harsh methods used to interrogate suspected terrorists in overseas prisons. This week, the head of the Senate committee, Sen. Dianne Feinstein, a Democrat, went public with complaints that the CIA was interfering with the investigation.
Q: Why is Washington still arguing about this?
A: When Obama took office five years ago, he quickly acted to ban "enhanced interrogation" methods, close the secret prisons and release the Bush-era legal opinions that had authorized the program. Just two months later, Feinstein's committee began its investigation, and soon discovered how arduous a task it can be to unravel the past. The committee has had to plod through 6.2 million pages of CIA documents, shared under strict ground rules that allow investigators to review them only at a CIA-controlled secure site in northern Virginia.
Q: Why is Feinstein so upset with the CIA?
A: Feinstein alleges a long pattern of CIA cover-ups:
--destroying videotapes of some of the first enhanced interrogations of Sept. 11 suspects.
--dumping millions of pages of electronic documents on the Senate investigators with no index or organization.
--secretly taking back hundreds of the pages from the document cache.
--snooping through the Senate investigators' computers to see if they had read an internal CIA review, and accusing those investigators of viewing it illegally.
Q: What does CIA Director John Brennan say?
A: He denies hacking into the Senate investigators' computers and says the agency has cooperated.
He says that Senate investigators may have "improperly obtained and/or retained" sensitive CIA documents, in violation of the ground rules for how the classified materials would be handled. The agency's acting general counsel has asked the Justice Department to look into whether Senate staffers committed a crime.
Q: Will anybody be charged with a crime?
Both sides have asked the Justice Department for a criminal investigation, but that's no guarantee that will happen. This involves a murky area of the law and it's not clear that prosecutors will want to get in the middle of this government dispute.
Q: Is this another partisan fight between Democrats and Republicans?
A: Not this time. It's more complicated.
Feinstein, typically a staunch defender of intelligence agencies, is squaring off against a CIA director who appears to have strong backing from his boss, the president. Brennan was Obama's counterterrorism adviser before taking the CIA job.
Brennan also served in the CIA during the Bush years, when the harsh interrogations were carried out.
Q: What are Republicans saying about all this?
A: Not much, yet.
Many say they are waiting for more facts to come out. The top Republican on the Senate Intelligence Committee, Sen. Saxby Chambliss, indicated he differs with Feinstein on her accusations against the CIA, but he hasn't elaborated.
The committee's Republican members declined to help write the classified report, seeing it as too critical. Yet some Republicans, such as Sen. John McCain, have spoken out against the interrogation methods.
House Speaker John Boehner, a Republican, says he is concerned about the allegations of snooping on Senate investigators. Lawmakers tend to put aside partisan differences if they believe that Congress' power is coming under threat from the executive branch.
Q: What does the Senate report say?
A: That's still secret. What's publicly known is that it's 6,300 pages and that the CIA disputes significant parts. It describes treatment "far different and far more harsh" than what's previously been described, according to Feinstein. She calls the detention and interrogation programs "brutal" and "un-American."
The report casts doubt on the intelligence value of the detention and interrogation program. The CIA disagrees and has contended the program helped track down Osama bin Laden.
Q: What kind of brutality is Feinstein talking about?
A: It's not clear what new information might be in the report. In addition to waterboarding -- pouring water over the face of a bound prisoner to create the sensation of drowning -- Feinstein has referred previously to abuses including beating a prisoner, who later died in custody, with a heavy flashlight; staging a mock execution; threatening to kill a detainee's family; and choking a suspect to the point of unconsciousness.
Q: Will the report ever see daylight?
A: Expect to get a look at parts of it. Feinstein's committee is making final revisions and updates. Congressional investigators want the Obama administration to declassify the report's 20 conclusions and its executive summary, which runs more than 300 pages. Brennan has promised to work with the Senate on declassifying portions of the report, and Obama supports its release as well. He's ready to move on.
Associated Press writers Kimberly Dozier and Eric Tucker contributed to this report.
Follow Connie Cass on Twitter at https://twitter.com/ConnieCass
Follow Nancy Benac on Twitter at http://twitter.com/nbenac