When it comes to the "secret kill list"—a regularly updated chart showing the world's most wanted terrorists—President Barack Obama is the "final moral calculation" in the kill or capture debate, according to the third in a series of New York Times articles assessing his record.

And despite his liberal background, Obama has taken an aggressive approach to counterterrorism.

The Times said it interviewed three dozen current and former advisers to Obama, who described his "evolution since taking on the role, without precedent in presidential history, of personally overseeing the shadow war with Al Qaeda":

They describe a paradoxical leader who shunned the legislative deal-making required to close the detention facility at Guantánamo Bay in Cuba, but approves lethal action without hand-wringing. While he was adamant about narrowing the fight and improving relations with the Muslim world, he has followed the metastasizing enemy into new and dangerous lands. When he applies his lawyering skills to counterterrorism, it is usually to enable, not constrain, his ferocious campaign against Al Qaeda—even when it comes to killing an American cleric in Yemen, a decision that Mr. Obama told colleagues was "an easy one."

Part of Obama's "evolution" on terror apparently began early in his term, when a drone strike resulted in civilian casualties:

Just days after taking office, the president got word that the first strike under his administration had killed a number of innocent Pakistanis. "The president was very sharp on the thing, and said, 'I want to know how this happened,'" a top White House adviser recounted. In response to his concern, the C.I.A. downsized its munitions for more pinpoint strikes. In addition, the president tightened standards, aides say: If the agency did not have a "near certainty" that a strike would result in zero civilian deaths, Mr. Obama wanted to decide personally whether to go ahead.

"The care that Mr. Obama and his counterterrorism chief take in choosing targets," the Times said, "and their reliance on a precision weapon, the drone, reflect his pledge at the outset of his presidency to reject what he called the Bush administration's 'false choice between our safety and our ideals.'"

Story continues

[Related: Terror plans hidden in porn?]

And Obama's success limiting civilian deaths in drone strikes is, in part, due to "a disputed method for counting civilian casualties" embraced by Obama. According to the Times, the White House considers "all military-age males in a strike zone as combatants ... unless there is explicit intelligence posthumously proving them innocent."

Obama's personal involvement in counterterrorism operations can be seen in his study of the "baseball card"-like "kill list." For example, in January 2010, Obama questioned the ages of some of the al-Qaida suspects on it.

"How old are these people?" Obama asked during his regular Tuesday briefing with intelligence officials--dubbed the "Terror Tuesday" meeting—in the White House Situation Room. "If they are starting to use children, we are moving into a whole different phase."

[Related: Calif. 9/11 fund raided for deficit]

The White House has also struggled with the so-called "Whac-A-Mole" approach to counterterrorism—an al-Qaida leader killed in, say, a drone strike is simply replaced with another.

"One guy gets knocked off, and the guy's driver, who's No. 21, becomes 20?" William M. Daley, Obama's chief of staff in 2011, told the Times. "At what point are you just filling the bucket with numbers?"

More popular Yahoo! News stories:

• Marco Rubio visits Guantanamo Bay in Cuba

• Ohio Democratic Party Chairman on Rob Portman: 'He's polite … not a pain in the ass'

• Polls: Obama leads Romney in Florida, Ohio and Virginia

Want more of our best political stories? Visit The Ticket or connect with us on Facebook, follow us on Twitter or add us on Tumblr. Handy with a camera? Join our Election 2012 Flickr group to submit your photos of the campaign in action.