President Obama acknowledged Thursday that U.S. drone strikes are responsible for the death of innocent bystanders, but still defended these attacks as an effective way to take out terror leaders or training camps, and argued that they lead to far fewer civilian casualties than conventional warfare.

He also argued that more effective means of carrying out attacks, such as those seen in the movies, aren't yet available.

"I wish I could just send an Iron Man — I don't mean that as a joke," he said. "I wish that the tragedy of war, conflict, terrorism, etc., did not end up creating circumstances where we, wielding kinetic power, don't end up hurting anybody that shouldn't have been hurt."

"There is no doubt that some innocent people have been killed by drone strikes… it is not true that it has been, willy nilly, let's bomb a village," he said. "That's not how folks have operated."

"What I can say with great certainty is that the rate of civilian casualties in any drone operation is far lower than the rate of civilian casualties that occur in conventional war," he said.

Obama made the statements during a question and answer session with students at the University of Chicago law school. They came after reported this week that the administration had reinstituted "signature strikes" against military-age men on battlefields around the world, even if American officials don't know exactly who the targets are.

The president was asked why there was little transparency and legal accountability for his drone strike program, and he delivered a lengthy response, sometimes struggling to explain the arcane military and legal architecture governing the program.

The president used the Navy Seal raid that killed Osama bin Laden as an example. For that high-level operation, the U.S. put "our best people who operate as precisely and effectively as any group of individuals on the planet," he said. A number of bin Laden's family members who were not targets of the raid were killed in the process.

"It was actually a pretty high civilian casualty rate for the precision of the mission," he said. "…So, part of my job as president is to figure out how I can keep America safe doing the least damage possible in really tough, bad situations."

However, Obama said he doesn't have the luxury of not doing anything and feeling "as if my conscience is clear."

"I have to make decisions because there are folks out there who are genuinely trying to kill us and would be happy to blow up this room without any compunction, and who are actively trying to fin ways to do it," he said.

Earlier in his response, he discussed changes to the program he has put in place since taking office, including "architecture" involving senior level officials at the WH and in the intelligence community and military who weigh the risks of civilian casualties in any drone strike.

He said he hoped by the time he leaves office that there is not only and internal program "that governs the standards that we set," but also an "institutionalized process" that publicly reports on drone strikes on annual basis.