Leaked document: US waging drone warfare from Air Force base in Ramstein, Germany

America's burgeoning drone warfare operation is being operated with the help of the sprawling US air base in Ramstein, Germany, according to a newly obtained intelligence document.

The base functions as a kind of high-tech relay station between Predator and Reaper drone operators in south western US and targets in Yemen, Somalia, Afghanistan and elsewhere, according to information obtained by online whistleblower magazine The Intercept.

Operators control the machines from thousands of miles away, relying on screen footage to pinpoint targets and determine the success of a mission.

Ramstein's satellite uplink station is used to route communications between pilots sitting at command stations, according to the information revealed in a series of image sildes. Video from the drones is then routed back through Ramstein and relayed to US intelligence and military facilities around world. The Ramstein base is critical to the entire operation.

"Ramstein carries the signal to tell the drone what to do and it returns the display of what the drone sees. Without Ramstein, drones could not function, at least not as they do now," a source with knowledge of the system told the Intercept.

Former US Air Force drone operator Brandon Bryant, who ran more than 1,000 missions from America, told German media: "The entire drone war of the US military wouldn't be possible without Germany."

A 2010 budget request report backs that up. "Because of multi-theatre-wide operations, the respective Satcom Relay Station must be located at Ramstein Air Base to provide most current information to the war-fighting commander at any time demanded," concluded the report. The relay station would also be used to support the operations of a mysterious black ops Air Force programme known as "Big Safari," said the report.

The classified document reveals a network of facilities from desert command centers in the south western US with communications to Ramstein and on to Afghanistan, Djibouti, Bahrain and back to American National Security Agency offices in Washington and Georgia.

American and German officials have tended to downplay any cooperation over the US drone operation amid wide-ranging criticism of the targeted hits in Europe. The information could prove embarrassing to German Chancellor Angela Merkel. The nation has granted the US the right to use Ramstein, but only if its actions are legal. Some experts believe the drone operations may only be legally justified in German law if they occur in declared war zones.

In 2013 President Obama attempted to allay the German public concern in a speech in Berlin. "We do not use Germany as a launching point for unmanned drones," he said then.

Pentagon spokesman Maj. James Brindle responded to a request for comment from the Intercept saying that the US "conducts operational level planning, monitoring and assessment of assigned airpower missions throughout Europe and Africa," at Ramstein, but does "not directly fly or control any manned or remotely piloted aircraft."

Ramstein is one of the largest US military bases outside America, with more than 16,000 personnel.