The US campaign of drone strikes in Pakistan's northwestern tribal belt is terrorising civilians 24 hours a day and breeding bitter anti-American sentiment, researchers say.
The attacks in northwest Pakistan, where militants linked to Taliban and al-Qaeda have strongholds, have killed thousands of people since they began in June 2004, according to the report by experts from Stanford Law School and the New York University School of Law.
Aside from casualties, the Living Under Drones report said, the missile strikes are affecting daily life in the tribal areas, making people unwilling to gather in groups and even stopping their children going to school for fear of being targeted.
After attacks, rescuers are unwilling to help the wounded for fear of being hit by follow-up missiles, said the report commissioned by UK-based charity Reprieve, which campaigns against drone strikes.
"Drones hover twenty-four hours a day over communities in northwest Pakistan, striking homes, vehicles, and public spaces without warning," the report said.
"Their presence terrorises men, women, and children, giving rise to anxiety and psychological trauma among civilian communities.
"Those living under drones have to face the constant worry that a deadly strike may be fired at any moment, and the knowledge that they are powerless to protect themselves."
The report urged Washington to rethink its drone strategy, arguing it was counterproductive and undermined international law.
Based on media reports and interviews with residents of North Waziristan, one of the areas most heavily targeted by drones, the research said the US conception of the campaign as a "surgically precise and effective tool that makes the US safer" was false.
Drone strikes allow the United States to carry out "targeted killings" of people it believes are militants from afar, without endangering American lives, but the campaign has become a festering sore in US-Pakistan relations.
Islamabad says the strikes are counterproductive and a violation of its sovereignty, but US officials are believed to regard them as an effective way of disabling terror groups by killing key members.
The Stanford-NYU report said "the publicly available evidence that they have made the US safer overall is ambiguous at best" and the majority of militants killed by drones seemed to be low-ranking.
US credibility across the region is suffering, the report said, and there is strong evidence the strategy is making it easier for militant networks to recruit new members.
Many of the Waziristan residents the researchers interviewed said they had been turned against the US by the drones.
"Before the drone attacks, we didn't know [anything] about America. Now everybody has come to understand and know about America... Almost all people hate America," one said.
Citing a CNN report, the Stanford-NYU paper said only around two per cent of those killed in drone strikes were "high-level" targets.
Total deaths between June 2004 and September 2012 were between 2562 and 3325, with 474 to 881 of them civilians, Living Under Drones said, quoting figures gathered from media reports by the London-based Bureau of Investigative Journalism.