Reporter: Obama has declared the world a battlefield

President Barack Obama laid out the legal argument on why drone strikes that killed four Americans were not only legal, but his presidential duty. He used the example of Anwar al-Awlaki, an American citizen and al Qaeda propagandist killed by a drone strike in Yemen almost two years ago.

"I would have detained and prosecuted Awlaki if we captured him before he carried out a plot. But we couldn't. And as President, I would have been derelict in my duty had I not authorized the strike that took out Awlaki," Obama said Thursday.

"The president said that he would have detained and prosecuted Anwar [al]-Awlaki, if that's the case, why did he never seek an indictment against Awlaki?" asked Jeremy Scahill, author of "Dirty Wars," a book on the United States' covert wars. Scahill is also the national security correspondent for "The Nation."

"Awlaki may have been guilty of all sorts of heinous activity, but no public evidence was ever presented against him, just pronouncements, usually in the forms of leaks from the White House," said Scahill.

Scahill said the president's speech was just an articulate re-branding of former President George W. Bush's policies.

"Effectively Obama has declared the world a battlefield, and reserves the right to drone-bomb countries in pursuit of people against whom we may not even have direct evidence, or that we're not seeking any indictments against," said Scahill.

There are no legal justifications for drone strikes against Americans, he said.

Three of the four Americans killed in drone strikes had never been charged with any crime. The U.S. had an indictment against the fourth, Jude Mohammad, killed in Pakistan.

Scahill said the U.S. had sought an indictment against one of the Americans, Samir Khan, and failed to get it.

"He was killed anyway," said Scahill.

On the killing of al Awlaki's son,  Abdul Rahman, Scahill said it is "just shameful that this administration will not explain why they killed this 16-year-old kid."

The administration has said Rahman was not specifically targeted.

"Are they implying that he was collateral damage?" asks Scahill. "That family and the American people have a right to know why this kid was killed."

Scahill's book "Dirty Wars" is now a documentary and will premiere next month. He said the most interesting thing he uncovered during the making of the documentary, was that the Obama administration is contracting out dirty work.

"While saying that they shut down the black sites, and they did, and saying that they don't torture anymore, [they] are actually using in Somalia a network of war lords to do the killing for America," said Scahill.

"They are outsourcing and directing foreign nationals to do it," said Scahill. "That really is a metaphor for how little things have changed on this particular front."