President Obama: "I'm Really Good At Killing People."

According to the new book "Double Down," in which journalists Mark Halperin and John Heilemann chronicle the 2012 presidential election, President Barack Obama told his aides that he's "really good at killing people" while discussing drone strikes.

Obama oversaw the 2009 surge in Afghanistan, 145 Predator drone strikes in NATO's 2011 Libya operations, the May 2011 raid that killed Osama bin Laden, and drone strikes that killed the Pakistani Taliban leader and a senior member of the Somali-based militant group al-Shabab this week.

His administration also expanded the drone war: There have been 326 drone strikes in Pakistan, 93 in Yemen, and several in Somalia under Obama, compared to a total of 52 under George Bush.

In 2011 two of those strikes killed American-born al-Qaeda propagandist Anwar al-Awlaki and his American-born, 16-year-old son within two weeks.

Under Obama U.S. drone operators began practicing "signature strikes," a tactic in which targets are chosen based on patterns of suspicious behavior and the identities of those to be killed aren’t necessarily known. (The administration counts all "military-age males" in a strike zone as combatants.)

Furthermore, the disturbing trend of the "double tap" -- bombing the same place in quick succession and often hitting first responders -- has become common practice.

Obama has also embraced the expansion of capture/kill missions by Joint Special Operations Command (JSOC) after it developed into the primary counterterrorism tool of the Bush administration.

One JSOC operator told investigative journalist Jeremy Scahill, author of "Dirty Wars: The World Is A Battlefield," that global operations under Obama became "harder, faster, quicker -- with the full support of the White House."

Scahill, who also made a "Dirty Wars" documentary, told NBC News that Obama will "go down in history as the president who legitimized and systematized a process by which the United States asserts the right to conduct assassination operations around the world."

Needless to say, a lot of innocent people have been killed along with combatants.