The secret CIA program halted last month by Director Leon E. Panetta involved establishing elite paramilitary teams that could be inserted into Pakistan or other locations to capture or kill top leaders of the Al Qaeda terrorist network, according to former U.S. intelligence officials.
The program -- launched in the immediate aftermath of the Sept. 11, 2001, terrorist attacks -- was never operational. But officials said that as recently as a year ago CIA executives discussed plans to deploy teams to test basic capabilities, including whether they could enter hostile territory and maneuver undetected, as well as gather intelligence and track high-value targets.
The initiative evolved through multiple iterations, and was close to being scrapped several times as CIA officials struggled to find solutions to daunting logistical challenges. But even as the Predator drone emerged as a potent new weapon against Al Qaeda, CIA officials continued to pursue the secret program as an additional lethal option.
"You always want to have capacity because you cannot predict opportunities," said a former senior U.S. intelligence official with extensive knowledge of the program.
With the emergence of the Predator, the official said, "we still wanted to explore having that capacity, but there wasn't the same sense of urgency that may have existed before."
That official and others spoke on condition of anonymity given the acute sensitivity of the issue.
CIA spokesman Paul Gimigliano declined to comment on the nature of the program.
The existence of the program, and the fact that it was kept secret from lawmakers for nearly eight years at the direction of former Vice President Dick Cheney, has fanned an already heated atmosphere in Washington over the Bush administration's intelligence programs.
Current and former U.S. intelligence officials have said that in terminating the program, Panetta may have been more concerned about the fact that the initiative had been kept secret from Congress than he was about the merits of the program.
A U.S. intelligence official said Panetta has not ruled out reviving an effort to develop a similar close-range capability in closer collaboration with lawmakers.
"If the United States ever needs something like this in the future, we'll find better ways to build it," the U.S. intelligence official said. "That includes briefing Congress earlier on. Panetta understands all that. He's an aggressive proponent of counter-terrorism, pushing tools and tactics that work and have the support to be sustainable. This one didn't."
Leading Democratic lawmakers have said it was illegal for the CIA not to disclose the program to intelligence committees, and called for an investigation.
"Individuals who ordered that Congress be kept in the dark should be held accountable," Sen. Russell D. Feingold (D-Wis.), a member of the Senate Intelligence Committee, said Monday. Feingold also said he had expressed "deep concerns about the program itself" in a classified letter to President Obama.
Sen. Dianne Feinstein (D-Calif.), the chairwoman of the Senate Intelligence Committee, said the former vice president may have broken the law by instructing the CIA to keep the program secret.
But current and former U.S. intelligence officials said that Cheney's role has been mischaracterized, and that the agency was not obligated to disclose the program because it was never close to being operational.
The former officials said that Cheney was never involved in managing the program, and that his instruction not to brief Congress came shortly after the initiative was first proposed.
"It was more like, before you go around and start talking about this, see if it is something you can make happen," said one of the former officials.
Legal authorities for the program were grounded in a comprehensive memorandum that President Bush signed just days after the Sept. 11 attacks, a 10-page document giving the agency powers to pursue Al Qaeda targets with lethal force.
A 1976 order signed by President Ford banned the CIA from carrying out assassinations. But that prohibition does not apply to killing enemies in war.
Panetta ordered the program terminated immediately after learning of it last month, and called emergency meetings with the House and Senate intelligence committees the next day to brief them.
The U.S. intelligence official defended Panetta's decision to dismantle the program, saying that it "never fully took shape" and "was derailed repeatedly over the years by concerns about its feasibility. So killing it cost virtually nothing in operational terms."
The program was launched at a time when then-CIA Director George Tenet and other top agency officials were scrambling to sort out what the agency would do if it could determine the location of Osama bin Laden or other high-level Al Qaeda figures.
CIA officials quickly endorsed the idea of developing small paramilitary teams that could carry out "surgical" strikes on high-value targets. But the program repeatedly bogged down on basic operational and logistical questions.
"Do you put them in Waziristan and sit there and wait?" said a second former U.S. intelligence official with knowledge of the program. "It's one of these things that makes a lot of sense until you start trying to make it work."
The official described internal debates over whether the teams should come out of the CIA's Special Activities Division -- its longtime paramilitary wing -- or whether they should be developed in partnership with U.S. military special operations forces.
The military was faulted after Sept. 11 for its tendency to require elaborate plans and large backup forces even for small-scale operations, a factor that had played into failures to capitalize on opportunities to catch or kill Bin Laden before 2001.
The former U.S. intelligence official said the program was designed to provide an option beyond guided bombs or Hellfire strikes from Predator aircraft.
The initiative was also focused exclusively on the top figures in the Al Qaeda chain of command, the former official said, dismissing suggestions that the effort was aimed at assembling teams of assassins that would roam the world looking for lesser terrorist targets.