Jane Mayer, the New Yorker writer who published in October 2009 one of the most penetrating stories on targeted killings by drones, said the Predators were “much more than just a breakthrough in technology—they were also a new frontier legally, politically, and morally.” In an e-mail interview, she described an intricate policy behind the secrecy: “It’s not, technically speaking, something that can be done under cover. But when the CIA is asked directly and on the record about its role, it denies having one.”

International politics play a role in that decision. The US government’s official denial, Mayer continued, “is in large part in deference to the Zardari administration in Pakistan, which prefers to mislead the Pakistani public about its acquiescence to the US drone strikes.” That acquiescence was always conditional and uncomfortable between the two allies, each of whom harbors suspicions of the other. In mid-April, Pakistani officials demanded that the CIA dramatically reduce its presence in Pakistan and that drone strikes cease, according to news reports, but, like so much of the US operations in Pakistan, it is unclear what is actually happening there.

In an interview with this author published by Newsweek earlier this year, former CIA acting general counsel John A. Rizzo pulled back the curtain a little and described the protocol set up to authorize a drone strike. One of the approximately ten lawyers in the CIA’s counterterrorism unit would review intelligence information and draft a memo asserting that an individual posed a risk to the security of the United States. After weighing the evidence in the memo, Rizzo, who retired in December 2009, would sign his name, noting that he “concurred.” The strike was then authorized.

Despite Rizzo’s unusual candor in that interview, he and other officials have fought to keep most information about the Pakistan drone war out of the public eye. Journalists have been unable to get answers to legal questions such as on what basis the government decides to kill. This is known as “distinction” in international law; in other words, how are those CIA lawyers discriminating between civilians and non-civilians who pose a grave threat to the United States? Also, how many civilian deaths can be justified? This is the question of “proportionality” in international law.

At this point, so little has been written about the way the CIA chooses its targets and executes its missions that some legal scholars argue it is impossible to know whether the program is legal. “I’ve been concerned that we don’t have the right kind of permission from elected officials,” said Mary Ellen O’Connell, an international law professor at the University of Notre Dame Law School. “Pakistan is not Somalia. They have a government we respect. It can be a weak government, but international law doesn’t allow you to act as if there is no government.”

A spokesman for the White House National Security Council, who spoke only on condition he not be named, rebuffed questions about why the administration refuses to speak with reporters on the record about the program. “You’re going to have a lot of people on the outside, and they all love to talk,” he said. “We can’t do that.” And, the official added, if outsiders are talking about the drone war, “that means they don’t know very much.”

Ignatius, of the Post, explained that Obama administration officials are sometimes willing to discuss drone operations in an attempt to promote the White House’s counterterrorism strategy. In February 2010, for instance, Ignatius was able to write a detailed account of the escalation of drone strikes because officials were eager to demonstrate that Obama was more aggressive in his pursuit of al Qaeda than Bush was.

“These rules about covert activities can be bent when it becomes politically advantageous,” Ignatius said. “When it suits them, you get quite a detailed readout.”

Tara McKelvey is the author of Monstering: Inside America's Policy of Secret Interrogations and Torture in the Terror War and is a 2011 Guggenheim Fellow. Research assistance was provided by Jed Bickman of the Investigative Fund at The Nation Institute, which also provided financial support for preparation of this article.