In this Jan. 31, 2010, file photo, an unmanned U.S. Predator drone flies over Kandahar Air Field in southern Afghanistan. (Kirsty Wigglesworth/AP)

The revelation last month that a CIA drone strike in Pakistan had killed an American hostage has reawakened a long-running debate on whether the intelligence agency should be in the drone business at all, or if such lethal strikes are best left to the military.

Sen. John McCain (R-Ariz.), chairman of Senate Armed Services Committee, said last week that he would use this year’s defense authorization bill to promote such a shift. The Senate Intelligence Committee’s chairman and ranking Democrat indicated that they would oppose him.

The public disagreement has exposed a legislative turf battle that began nearly two years ago, when President Obama said he favored military control. He still does, according to the White House.

But with the military-intelligence divide on Capitol Hill reflecting similar differences between the Defense Department and the CIA, the president has not taken action either way.

Obama “has explained his belief that we must be more transparent about both the basis of our counter­terrorism actions, including lethal operations, and the manner in which they are carried out,” said National Security Council spokesman Edward C. Price.

“He has indicated that he will increasingly turn to our military to take the lead and provide information to the public about our efforts,” Price said. “We continue to work diligently toward this goal.”

The deaths of al-Qaeda hos­tages Warren Weinstein and Giovanni Lo Porto, an Italian aid worker, in the CIA drone strike have “rekindled the debate and maybe given it some new momentum,” said Rep. Adam B. Schiff (Calif.), the senior Democrat on the House Intelligence Committee. Schiff has bucked the predominant view, at least on the Senate intelligence panel, and said he favors military control.

Schiff disagrees with Sen. Dianne Feinstein (Calif.), the senior Democrat on the Senate Intelligence Committee, who said last week that “we have much more oversight over the intelligence program than we have over the military program, and that’s just a fact.”

Feinstein and others have argued that the CIA is better at lethal strikes and, despite Weinstein’s accidental death, is responsible for less collateral drone damage than the military.

“I haven’t seen any evidence that the DOD is not perfectly competent to do this,” Schiff said in response. “I think people are going more on their gut sense than any empirical data.”

The administration has said that turning the program over to the military would allow it to be more transparent than it can be about CIA drone strikes, which are considered covert actions that can be disclosed only with presidential permission.

But the deaths of Weinstein and Lo Porto marked the first time the administration has acknowledged civilian deaths in a strike by either the CIA or the military outside of war operations in Afghanistan. Witnesses, human rights organizations and even partner governments have reported numerous instances of such unintended consequences from CIA drone strikes in Pakistan since 2008 and strikes conducted by the CIA and the military’s Joint Special Operations Command in Yemen.

Speaking from the White House on April 23, President Obama said government officials had worked "tirelessly" to return Warren Weinstein to the U.S. before he was accidentally killed by a U.S. operation while being held by al-Qaeda. (AP)

Although figures vary among independent tallies, the Bureau of Investigative Journalism has documented 415 strikes in Pakistan and Yemen since the Sept. 11, 2001, terrorist attacks, the vast majority of them under the Obama administration. The organization estimates that from 423 to 962 of those killed have been civilians. The administration has said those casualty figures are greatly inflated, while offering no accounting of its own.

Regardless of what Congress decides, Schiff said, “there is nothing to prevent the administration from being more transparent any time they decide they want to be” by providing “an annual accounting of how many people have been killed — civilians and combatants — and how they are defining each. There is no reason why this should require legislation,” although both he and Feinstein have proposed bills ordering Obama to provide the figures.

But “to argue that this is solely about who is better at collateral-damage issues is to miss the wide array of added strategic, political, legal and ethical issues at play,” said Peter W. Singer, a senior fellow at the New America Foundation who specializes in modern warfare. “There are fundamental differences when a campaign is being designed, authorized and operated under military command and control versus . . . civilian intelligence agencies.”

Questions include “how are you putting this within an overall strategy,” Singer said. “The lawyers involved . . . the arguments they make for or against, the laws they turn to for guidance . . . the reporting of it. Then, the feedback loop of both how it goes well and what happens when it goes bad.”

There is a clear history of accountability for strikes gone awry in the Afghan war, including courts-martial and payments made to bereaved citizens on the ground, he said. But none of that occurs when the military is involved in drone attacks under the auspices of clandestine counter­terrorism operations.

When Obama first announced new lethal targeting guidelines and a push toward military control in a 2013 speech, administration officials said that one of their principal goals was to establish a “playbook” that would lock down the rules for future administrations.

But by not fully implementing his own changes, Obama has left the issue open for the next president. It is early in the 2016 campaign “and no one’s talking about it,” Singer said. All declared and likely candidates have been generally supportive of the drone program.

The administration is also using armed drones as part of its air campaign in Iraq and Syria against the Islamic State, whose global footprint is expanding across the Middle East and into Africa and Southeast Asia. “Now we get to the real nitty-gritty,” Singer said. “Who will control” an expansion against the Islamic State.

Another goal of the administration playbook was to set rules — and an example — that could be imposed on other countries. Nations now flying armed drones include Britain, Israel, Nigeria, Iran, Pakistan and China, while a number of others are developing them.