As US President Barack Obama completes his second term, the controversial drone strikes he has dramatically escalated will clearly be part of his legacy.

Reports show that the US military launched a drone strike on May 21 that killed Taliban leader Akhtar Mohammad Mansour in a western Pakistan province near the border with Afghanistan.

There have been no reports about whether Pakistan's government was informed beforehand of the strike that took place on its sovereign territory. Neither was there any information on the others blown up in the vehicle by several US drones.

The US government has been using euphemisms to describe such action as target killing, rather than assassination, just like the words "enhanced interrogation" instead of "torture" are used regarding Guantanamo prison detainees held without due process.

While Obama's claim that the US has been the "standard bearer in the conduct of war", the drone strikes have drawn sharp criticism over their legality and the loss of civilian lives, described in White House euphemism as "collateral damage".

In such a situation, Obama, a lawyer by training, has been making decisions himself as who should be on the kill list. This contrasts sharply to his days as a young senator from Illinois when he criticized such a counterterrorism approach by then-President George W. Bush.

The latest book, The Assassination Complex: Inside the Government's Secret Drone Warfare Program, written by Jeremy Scahill and the staff of The Intercept and published by Simon & Schuster early this month, tells an entirely different story from the one by Obama and other US government officials.

The book is based on the Drone Papers published by The Intercept last October with numerous secret documents by whistleblowers that detail the inner workings of the US military assassination program in Afghanistan, Yemen and Somalia.

Far from Obama's claims that drone strikes have been carried out with "near certainty", the book shows that some 90 percent of the people decimated in the strikes were not the intended targets.

It was not what Obama said at a press conference during the Nuclear Security Summit in Washington in early April, even when he admitted that civilians were killed.

"It wasn't as precise as it should have been, and there's no doubt civilians were killed that shouldn't have been. ... We have to take responsibility where we're not acting appropriately, or just made mistakes," Obama said.

The commander-in-chief then defended the program by saying "we've worked very hard to avoid and prevent" those strikes and "our operating procedures are as vigorous as they've ever been".

It might be true that with the emergence of remote-controlled lethal weapons, the US may have saved American lives by not putting boots on the ground, but what is also true is that the cost of civilian lives in those countries from South Asia to the Middle East and North Africa has increased dramatically.

The Intercept papers and book reveal that the strikes personally ordered by Obama could often be based on an intelligence system with many loopholes, and that the US military simply labels unknown people killed in drone assassination as "enemies killed in action".

The publications also reveal that White House standards regarding drone strikes are confusing. For example, the White House policy standards stipulate that lethal force will be used only against targets who pose a "continuing, imminent threat to US persons". It does not fit the situation in Yemen and Somalia, where there was little US presence to justify such action.

The Intercept papers and books are among some of the revelations of Obama's heinous drone-assassination program.

The documentary National Bird, directed and produced by Sonia Kennebeck and released last month, tells the story of the horrible drone program from the viewpoint of three US whistleblowers, or three US military veterans who participated in the drone warfare but were haunted by the guilt of killing people on foreign soil, people whose faces they could not even see.

The prolonged psychological horror suffered by civilian survivors of those drone strikes is also revealed in the documentary.

The White House announced in March that it will release its drone playbook and the number of casualties regarding combatants and civilians. What is clear is that the whole world is watching this legacy of Obama's, while drone technology continues to proliferate around the world.

Remember the panic caused in the US when a small amateur drone crash-landed last October on the Ellipse, the lawn outside the White House?

Contact the writer at chenweihua@chinadailyusa.com