On the American president's ever-expanding list of powers, here's the most unsettling: the ability to assassinate anyone he chooses, far from any theatre of war.

We don't like to think of a democratically elected head of state sitting before a list of names in an air-conditioned office, deciding who lives and dies. But that's the picture of Barack Obama and John O Brennan, his counter-terrorism chief, that's painted in two new investigative reports.

The two men sit at the top of a massive executive pyramid tasked with tracking down and taking out the country's enemies: in effect, deciding who America will target each week for extrajudicial killings.

'A no-brainer'

As a campaigning senator and a wartime president, Obama has been fairly consistent on this point. He promised to disengage the US from the wars in Iraq and Afghanistan and refocus attention on al-Qaida and transnational terrorist threats. In pursuing that goal, he's come to rely more and more heavily on predator drone strikes in Afghanistan, Pakistan, Yemen, and elsewhere – including a strike which killed Anwar al-Awlaki, an ambitious al-Qaida propagandist and US citizen, in Yemen last year. The president allegedly called that decision "a no-brainer".

Last week saw a series of drone strikes in Pakistan. Over the weekend, they continued: a strike in Afghanistan reportedly killed al-Qaida commander Sakhar al-Taifi.

Because the areas targeted are so remote, gathering independent evidence about the number of casualties is notoriously difficult. The Bureau of Investigative Journalism estimates that up to 3,145 people have died in total since 2004; of that, up to 828 were civilians. These are necessarily rough estimates, as the US authorities have always been very secretive about the operations.

But now, thanks to investigations by the Associated Press and The New York Times, we at least have a better idea of how the decision-making process works.

Here's what happens: a list of possible terrorism suspects is drawn up during a weekly secure video conference meeting between members of the government's national security branches. (The CIA, which runs the drone programme in Pakistan, has its own exclusive round tables.)

This has been dubbed the "nomination" process: to be nominated is to be greenlighted for capture or assassination. Brennan (whom the Times fondly calls a "priest with extremely strong moral values who was suddenly charged with leading a war") has taken charge of the programme; and the president personally approves every name on the "kill list".

Here's the start to the Times's thorough and eye-opening report:

This was the enemy, served up in the latest chart from the intelligence agencies: 15 Qaida suspects in Yemen with Western ties. The mug shots and brief biographies resembled a high school yearbook layout. Several were Americans. Two were teenagers, including a girl who looked even younger than her 17 years.

President Obama, overseeing the regular Tuesday counter-terrorism meeting of two dozen security officials in the White House Situation Room, took a moment to study the faces...

Death list, repackaged

The reports suggest that Obama has given the nod not only to "personality" strikes (which target designated individuals) but also "signature" strikes (which target training camps and compounds).

In addition to expanding the use of drones, the president has also adopted some of the most contentious war-on-terror policies of his predecessor, George W Bush. To begin with, the New York Times notes, Obama has retained the CIA's method of counting casualties of drone strikes: any man of fighting age killed in an attack is considered a militant.

He's also decided, via what's claimed is a legal loophole, to keep alive the CIA's controversial rendition programme, under which suspected militants are captured abroad and moved to another location for questioning.

What does all this mean?

Administration officials seem to advertise the fact that Obama has taken direct responsibility for the strikes and attendant casualties (both suspected militants and civilians). In a sense they're right to – a president should take responsibility for his controversial programmes. And his actions are in response to proven threats against the US.

But these troubling facts remain: the head of state of the most powerful country in the world is personally ordering extrajudicial killings on a regular basis – mainly in areas so remote that it is impossible to get an accurate number of casualties, or to determine how many innocent civilians the president has killed in his campaign to keep America safe.

As the Times puts it: "The administration’s very success at killing terrorism suspects has been shadowed by a suspicion: that Mr Obama has avoided the complications of detention by deciding, in effect, to take no prisoners alive."

Further reading: Learn more about the covert war on terror.