A Notre Dame University law professor says the legal and moral issues related to the U.S. government's use of unmanned drones to kill individuals in war zones could be more difficult than similar issues on torture.

"There is a seductive quality of killing with drones" because they are high-tech and sleek, said Mary Ellen O'Connell.

She referred to targeted deaths by drones as "extrajudicial" killings.

"International law does not support what the United States and other countries are doing with drones," she said.

Marjorie Cohn, professor at the Thomas Jefferson School of Law in San Diego, quoted an expert who called drones "a deadly surveillance platform." She cited a study that she said indicated drone attacks kill civilians at a significantly higher rate than do attacks by fighter jets.

"We don't see the pictures of children blown up by drones," said Cohn, who edited the book Drones and Targeted Killing.

Cohn and O'Connell spoke Saturday at the first Interfaith Conference on Drone Warfare at the Princeton Theological Seminary, which began Friday evening with 150 participants from about two dozen states and Finland. It was scheduled to wrap up on Sunday.

Organizers said it could be a historic meeting with Christians, Muslims, and Jews as well as officials from denominations including Catholic, Methodist, Quaker, Presbyterian, and others. It was modeled after a successful 2006 interfaith conference on torture held at the seminary.

"Torture was targeted at individuals, and drones are targeted at individuals. In that way, they are similar," said the Rev. Richard Killmer, project director of the conference, who retired in late 2013 as head of the National Religious Campaign Against Torture.

Religious organizations now seem to believe that legal and moral issues related to drone attacks by the U.S. government must be dealt with because drone attacks make it easier for nations to wage war, and because there are questions over the legal authorization of drone attacks, Killmer said.

Drones, or unmanned aircraft, do not require troops on the ground and do not put U.S. military lives at risk, as they are controlled electronically, Killmer said.

Conference participants were shown a film clip of the documentary Unmanned: America's Drone Wars on the civilian casualties from drone attacks that included emotional scenes of lost family members. Several "drone quilts" were displayed, quilts that memorialize civilians killed by drone attacks in combat zones.

The Rev. Chris J. Antal, of the Unitarian Universalist Congregation in Rock Tavern, N.Y., said he volunteered to be a military chaplain in Afghanistan in 2012 and served for five months. He said drone attacks troubled him deeply.

Antal said he believed he had volunteered to serve in a "just war on terror," but found the United States was "terrorizing civilians with drone strikes."

He added, "I had soldiers coming to me feeling the moral pain of being part of this."

Peace Action Education Fund, a nonprofit organization in Princeton that began as a nuclear disarmament group, helped organize the conference. The group calls itself the nation's largest grassroots peace and disarmament organization, with chapters in more than 30 states.

Participants had been assigned to listen to discussions over the weekend and to help draft policy recommendations for the U.S. government and religious organizations for national, local, and regional strategies.

Killmer said the conference grew out of a desire by religious organizations in Washington to discuss the issues and a willingness of the Peace Action Education Fund to organize it in Princeton.

Despite the inclement weather, there was only one cancellation. "The advantage of this being a national group, once you are here, you are here. You are not commuting from Arkansas," Killmer said.

Sister Rosemary Cauley, of the Grey Nuns of the Sacred Heart in Yardley, Bucks County, was one of the day trippers who attended the event. She said she had had second thoughts about driving across the Delaware River and, indeed, said it was frightening on the roads. But she thought she had to attend.

"This is part of a larger problem of our war-making mentality," she said.