US drones risk continual war, says report

The routine use of drones by the US to kill alleged terrorists offshore may be creating "a slippery slope leading to continual or wider wars" and is increasingly inconsistent with the rule of law, according to a major new report.

The report, produced by the Stimson Centre, a think-tank in Washington, also says that America's enemies which are far less discerning about the use of lethal unmanned aircraft could be emboldened to use drones against the US as the technology spreads.

MQ-1 Predator Unmanned Drone with Hellfire Missiles Flying at Sunset.
Erik Simonsen | Getty Images
MQ-1 Predator Unmanned Drone with Hellfire Missiles Flying at Sunset.

"We are concerned that the Obama administration's heavy reliance on targeted killings as a pillar of US counterterrorism strategy rests on questionable assumptions, and risks increasing instability and escalating conflicts," the report says.

US drone policy has come under heavy criticism largely from civil libertarians and left-of-centre groups but this report was produced with the help of an array of figures with lengthy experience in the US military and diplomatic establishment.

More from The Financial Times:
Pimco runs risks in turning up the 'vol'
Juncker nominated for Commission president
EU sets 3-day deadline for Russia to act on Ukraine peace plan

The primary authors of the report are a retired general, John Abizaid, a former US Central Command commander, and Rosa Brooks, a law professor and former Pentagon official under President Barack Obama.

Far from ending the threat of anti-US terror groups, the report notes that Sunni and Shia Islamist extremist groups have grown in scope, lethalness and influence in their areas of operation in the Middle East, Africa and South Asia.

"Furthermore, US strikes also create new strategic risks," it says, including the erosion of sovereignty norms and the threat of "blowback" against the US.

Read More Military dream come true: One system, many drones

According to the London-based Bureau of Investigative Journalism, the US carried out 376 drone attacks in Pakistan between 2004 and 2013, with the death toll between 2,500 and 3,600 individuals.

Reports in the Pakistan media have said up to one-third of those killed were civilians. Of all the "non-battlefield" targeted killings carried out by the US since 2002, 98 per cent have involved drones.

Mr Obama, in a major speech on US policy last year, said drone strikes "had saved US lives" by taking al-Qaeda commanders off the battlefield, and the attacks had been proportional, in self-defence and legal.

But the report is perhaps most critical of the evolving legal doctrine cited by both the George W Bush and Obama administrations to justify their strikes against "combatants" in the "war on terror."

Read More Dealing in Drones: The Big Business of Unmanned Flight

"The legal norms governing armed conflicts and the use of force look clear on paper, but the changing nature of modern conflicts and security threats has rendered them almost incoherent in practice," the report says.

"Basic categories such as 'battlefield', 'combatant' and 'hostilities' no longer have clear or stable meaning. When this happens, the rule of law is threatened."

The report recommends that the US conduct a rigorous cost-benefit review of the use of drone strikes and also increase the transparency surrounding them.

Read MoreThe US jet fighter that can do it all—maybe

Drone technology is already spreading rapidly around the world. In recent days, US officials have noted how Iran has been using drones to gather intelligence on the militant groups threatening the government in Baghdad.

In its latest annual report on the Chinese military, the Pentagon said it was "probable" that China used a drone for a reconnaissance mission in the East China Sea in 2013 and it had revealed details of four different drones under development.

It cited another Pentagon report that claimed the China drones programme enjoyed "unlimited resources" and "might allow China to match or even outpace US spending on unmanned systems in the future".

—By Richard McGregor, The Financial Times