The first drone strikes approved by the Obama administration in the new year killed a major Taliban leader in Pakistan but also fueled growing concerns about Obama's accelerated use of secret killings with little outside oversight.

According to Pakistani security officials, an American drone strike killed 14 persons, including Maulvi Nazir, who aided anti-U.S. fighters in Afghanistan.

Since becoming commander in chief, Obama has signed off on approximately 300 drone strikes in Pakistan alone, more than six times the amount approved by President George W. Bush, according to the New America Foundation, a Washington think tank. It's estimated that roughly 2,500 people have died in drone strikes conducted by the Obama administration.

A review by the Council on Foreign Relations concluded that between a few dozen and a couple hundred of those killed were innocent civilians. The Obama administration has given no official accounting of civilian deaths.

The public remains largely in the dark about the rules for killings ordered from thousands of miles away, critics said, raising the stakes for Obama in his second term to outline a coherent blueprint for using the weapon.

"None of the questions that are being raised in public are getting answered," said Steven Aftergood, director of the Federation of American Scientists' Project on Government Secrecy. "What is a reliable estimate of the number of casualties; what are the strategic consequences of targeted killings; what is the role of the CIA?"

There has been debate within the administration about the purpose of unmanned drones, according to several published accounts. Some argue the tool should be used solely if no other options are available, while others insist it's a centerpiece of limiting American casualties on the battlefield.

"One of the things we've got to do is put a legal architecture in place, and we need congressional help in order to do that, to make sure that not only am I reined in, but any president's reined in terms of some of the decisions that we're making," Obama said recently on "The Daily Show."

Supporters say Obama has proven the effectiveness of the drone campaign, eliminating a string of al Qaeda leaders and other threats to America.

"The administration's use of drones has been a remarkable success and appears to have made us safer as a whole, killing hundreds of dangerous militants with relatively few civilian casualties," said Jordan Tama, an intelligence and counterterrorism policy adviser to Obama's 2008 presidential campaign. "The American people support [targeted drone strikes] -- that's why there hasn't been an outcry."

A recent Pew survey found that 62 percent of Americans approved of the U.S. government's drone campaign against extremist leaders. However, most other nations in that same poll were against the U.S. effort, especially in the majority-Muslim nations where many of the strikes occur.

And critics say that if the public was more aware of the civilian casualties tied to such attacks, approval ratings for the technique would plummet.

Critics of the policy doubted that Obama has any incentive to change his tactics.

"I don't expect him to change course unless the pressure grows on him to explain how he determines who winds up on this kill list," said Christopher Preble, vice president for defense and foreign policy studies at the Cato Institute. "I wish that partisanship would work its magic and you'd have Republicans criticizing him for an abuse of power -- but they seem to like it."