Documents published by an investigative website and said to have come from a US intelligence community source portrayed the 14-year-long US drone system as unreliable and often the remote killer of innocents without judge or jury.

The Intercept said strikes often killed many more people than intended, contrary to assertions by President Barack Obama's administration that extrajudicial flights kill terrorists precisely and result in minimal casualties.

The website said the leaked electronic papers originated from a Pentagon study of various airstrikes in Afghanistan between 2011 and 2013 as well as in Somalia and Yemen - two nations on whom the US had not officially declared war.

Washington's practice billed as protecting US citizens from "imminent" threats and branded as "targeted killings" still amounted to assassination without indictment or trial, it said.

'Operation Haymaker'

One set of drone airstrikes in northeastern Afghanistan in January 2012 and February 2013 called Operation Haymaker resulted in the deaths of 155 persons, of whom only 19 were the intended targets, according to a listing displayed by The Intercept.

Diagrams depicted a command chain from intelligence sources on the ground right up to the president's Oval Office. Potential targets were placed on a watch list with personal details noted on so-called "baseball cards."

Persons killed but presumed to have been innocent were still classified as "enemies killed in action" or EKIA on the grounds of their close proximity to the target.

Intelligence from unconventional battlefields was "poor and limited." It took an average of 58 days for the president to sign off on a target. US forces then had 60 days to strike the suspect, The Intercept said.

Responding, White House spokesman Josh Earnest said US counter-terrorism operations around the world went to "great lengths to limit civilian casualties."

Remote executions

The Intercept claims followed a former drone operator's testimony in Berlin on Thursday that the US Ramstein airbase in Germany played a key role in a US drone network dependent on instantaneous satellite and glass fiber links.

Ramstein in Germany - part of the drone system?

Brandon Bryant, who quit the US military four years ago, told a German parliamentary inquiry committee that data on suspects from airborne drones was transmitted via Ramstein to crews who carried out remote executions.

The German news magazine "Der Spiegel" reported in April that such operators were located at US military bases in Nevada, Arizona or Missouri to avoid the hypothetical risk of German war crimes prosecution.

Germany reluctant to ask?

In 2010, a 20-year-old German from Germany's western city of Wuppertal was killed by a drone in Pakistan's restive Waziristan region.

Three years later, federal prosecutors dropped their probe into his death on the grounds that his links to jihadists had left him unprotected under international law.

To avoid diplomatic ructions, Chancellor Angela Merkel's government had adopted the stance of not raising questions after US assurances that Ramstein was not used to launch drones, Spiegel claimed.

Bryant told the Bundestag's NSA inquiry committee on Thursday that while operating drones he and other US service personnel were told that they were "working together with the [German] government."

When the German government knew a mobile telephone number and passed it on the American government this could be used to "execute" a person, Bryant testified.

'Assassination rather than capture'

Friday's article by The Intercept said President Obama's reliance on drones had resulted in a system that "suffers from an overreliance on signals intelligence, an apparent incalculable civilian toll, and - due to a preference for assassination rather than capture - an inability to extract potentially valuable intelligence from terror suspects."

It cites the drone missile killing of Briton Bilal al-Berjawi, who was killed in 2012 while driving a car near Somalia's capital, Mogadishu.

A secret 2013 Pentagon report showed that in the five years before his death intelligence services had monitored al-Berjawi as he moved back and forth between Somalia and London, The Intercept said. Britain had revoked his citizenship in 2010.

The Intercept said Hellfire missiles fired from drones were often aimed at mobile phones that disclosed the targeted person's locality.

'Outright lies'

The whistleblower quoted by The Intercept said US government statements that minimized the number of civilian casualties from drone strikes were "exaggerating at best, if not outright lies."

"It's a phenomenal gamble," the source said.

The Intercept said the source believed "the public has a right to understand the process by which people are placed on kill lists and ultimately assassinated on orders from the highest echelons of the US government.“

The investigative website was co-founded by award-winning journalist Glenn Greenwald, who published documents leaked by former US intelligence contractor Edward Snowden detailing massive electronic surveillance by US intelligence agencies.

ipj/kms (dpa, AFP)