WASHINGTON  — The constant buzzing of weaponized drones flying overhead and the dreadful hiss of Hellfire missiles are a feared part of life among civilians in some villages far away from the borders of the United States.

And, with the March 25 news that the San Diego Military Advisory Council and the San Diego Regional Economic Development Corp. are seeking to create a "drone zone" in southern California, the U.S. government’s biggest open secret — the use of aerial drones for targeted killing of alleged terrorists and their associates — has come under renewed moral scrutiny by Catholic theologians and just-war theorists.

Kentucky Sen. Rand Paul’s nearly 13-hour filibuster of CIA Director John Brennan’s confirmation on March 6 put the U.S. government’s targeted killing of suspected al Qaeda militants and associated forces with strikes by unmanned aerial vehicles (UAV), or drones, back into the national spotlight. The Republican senator’s filibuster was linked to Brennan’s lead role in the authorization of drone strikes while serving as the White House’s counterterrorism adviser.

"No one person, no one politician should be allowed to judge the guilt, to charge an individual, to judge the guilt of an individual and to execute an individual," Paul said. "It goes against everything that we fundamentally believe in our country."

Most Americans (57%) support the president’s drone war against terrorists, according to a Pew Research Center poll conducted in February. But 53% of Americans say they are "very concerned" about civilian casualties, including 42% of those who support the drone-war program.

President Barack Obama and White House officials have touted the targeted killings by drones as a valuable tool in the war on terrorists authorized by Congress’ "Authorization of the Use of Military Force." The White House says the program has decimated the leadership of al Qaeda and its affiliates and had a severe effect on al Qaeda’s operations.

But the president’s conduct of the war, including vague criteria about what makes a legitimate target for killing through a drone’s "surgical strike," has caught the attention of Catholic bishops, moral theologians and just-war theorists.

 "The bishops are very much aware of this discussion going on in our nation, and they are certainly looking to bring the insights of our moral tradition to the question," said Stephen Colecchi, director of the U.S. Conference of Catholic Bishops’ Office of International Justice and Peace.

"The use of drones in the context of something like the so-called ‘War on Terror’ is not in itself something that is intrinsically wrong," said Christopher Tollefsen, a moral philosopher at the University of South Carolina. "It is something that can be used with good judgment and could be used legitimately."

Msgr. Stuart Swetland, a 1981 graduate of the U.S. Naval Academy and Archbishop Harry Flynn Chair of Christian Ethics at Mount St. Mary’s University in Emmitsburg, Md., explained that moral concerns over drone-targeted killings focus mainly on whether the strikes are proportionate — the good achieved is proportionate to the damage done to enemies — and discriminate between legitimate enemy combatants and non-combatant civilians.

"We put a value on defending the innocents in the other land, because the whole idea of fighting a just war is to bring about a just peace," Msgr. Swetland said.

Paradoxically, the U.S. drone warfare program remains an official secret, preventing the public from examining even the most basic facts of a war conducted in its name. The U.S. Justice Department has resisted in court a Freedom of Information Request by the American Civil Liberties Union requesting the CIA’s legal rationale for drone-targeted killings, the total number of killings, the total number of civilian casualties, program restrictions and geographic limits.

The U.S. has carried out 420 drone strikes against suspected terrorist militants in Pakistan and Yemen, killing between 1,967 and 3,236 suspected militants, according to media reports aggregated by the New America Foundation.

However, an emerging picture from independent investigative journalists and researchers casts doubt on the administration’s narrative that the strikes are "surgical" at all, suggesting that the narrative fails to acknowledge the full scope of civilian casualties and discounts evidence that many of the "militants" included in media-reported body counts may actually be innocent civilians.

The drone war involves two kinds of strikes: "personality strikes," where an individual suspected terrorist is targeted, and "signature strikes," where a Predator drone fires on individuals unknown to the CIA but who fit the CIA’s militant profile. A New York Times story in May 2010 reported that President Obama personally approves both kinds of strikes in weekly meetings with his advisers dubbed "Terror Tuesdays."

John Steinbruner, director of the University of Maryland’s Center for International and Security Studies, argued bad intelligence made Obama’s use of drones for targeted killings "in moral terms and practical terms very, very difficult to justify."

Steinbruner said human informants providing the CIA targeting data on suspected militants were both "inherently unreliable" and "prone to error."

But casualties as collateral damage of these strikes also pose a moral concern. Between 16%-25% of drone strikes in Pakistan have civilian casualties, according to data reported by the Bureau of Investigative Journalism. The London-based investigative outfit reports that as many as 884 civilians and 197 children may have been killed by drone strikes and 1,464 persons injured.

Msgr. Swetland said that Americans need to apply the "the Golden Rule" when it comes to evaluating civilian casualties and consider what they would accept if the war zone were Florida, not Pakistan’s Waziristan region.

"We should not be willing to inflict on our enemies any more than we would be willing to accept in trying to liberate our own people, with our own citizens being killed as collateral damage," Msgr. Swetland said.

But Steinbruner argued that the morality of all such civilian casualties was dubious, since few of the drone strikes are targeting militant leaders who conceivably could actually plot attacks against the U.S. Just 51 militants (2%) killed in drone strikes from 2004-2012 were leaders of al Qaeda or associated forces, according to the New America Foundation.

The Obama administration has justified these killings of low-level operatives on the basis that they pose an "imminent threat" to U.S. national security. A white paper leaked to NBC earlier this year revealed the White House believed any member of al Qaeda posed an "imminent threat" on the basis that al Qaeda is always planning attacks.

But Tollefsen said the Obama administration’s criterion was too "vague" to adequately meet the just-war standard. He said that standard requires more concrete evidence of a threat.

"If they are working on something, there are serious planning stages in it or it looks like they are carrying it out, then use of military force such as a military drone strike would be morally permissible," Tollefsen said, "provided certain other moral conditions are met."

Moreover, some analysts maintain the rate of civilian casualties may be even higher than is believed, in light of reports that the administration’s definition of an enemy combatant includes every military-age male in a strike zone.

One such example of a signature strike, according to the Stanford/NYU researchers, involved a March 17, 2011, U.S. drone strike in the town of Datta Khel, North Waziristan. An overhead drone killed 42 civilians, including tribal elders, gathered at a jirga, a meeting to resolve local conflicts and disputes, with two Hellfire missiles. Only 14 survived, but for U.S. purposes, the killed were all militants, even though only four present were, in fact, Taliban foot soldiers.

Tollefsen said targeting an area with civilians "might be permissible" only if the alleged target was "a very serious threat and that was the only opportunity they had to take him out."

A February 2012 report by the Bureau of Investigative Journalism independently confirmed 12 out of 18 media-reported U.S. drone attacks on rescuers and mourners at funerals. The United Nations has designated a special rapporteur to investigate such attacks as potential war crimes.

However, the drone-strike program’s real potential for blowback could also undermine its ability to fulfill just-war criteria if the drone strikes prove more effective at generating anger and terrorist violence toward the U.S. than at defeating al Qaeda.

"I think we need to rethink this," Msgr. Swetland said. He said just-war criteria requires that military action, such as drone strikes, be directed to concluding a just peace. But Americans, he said, have so far avoided the necessary discussion about the "long-term strategy and goals to get to the lasting peace we are looking for."

He said, "We may be losing the greater war on terror because we’re not building up the vision that America is not the great Satan the terrorists say we are."

Peter Jesserer Smith writes from

Rochester, New York.