The HRW said that the United States targeted airstrikes against alleged terrorists in Yemen killed civilians in violation of international law.
The strikes, often using armed drones, are creating a public backlash that undermines US efforts against Al-Qaeda in the Arabian Peninsula (AQAP).
The 102-page report, "'Between a Drone and Al-Qaeda': The Civilian Cost of US Targeted Killings in Yemen," examines six US targeted killings in Yemen, one from 2009 and the rest from 2012 to 2013.
Two of the attacks killed civilians indiscriminately in clear violation of the laws of war; the others may have targeted people who were not legitimate military objectives or caused disproportionate civilian deaths.
"The US says it is taking all possible precautions during targeted killings, but it has unlawfully killed civilians and struck questionable military targets in Yemen," said Letta Tayler, senior terrorism and counterterrorism researcher at Human Rights Watch and the author of the report.
"Yemenis told us that these strikes make them fear the US as much as they fear Al-Qaeda in the Arabian Peninsula," Tayler added.
Human Rights Watch released the report in a joint news conference on October 22, 2013, with Amnesty International, which issued its own report on US drone strikes in Pakistan.
During six weeks in Yemen in 2012-2013, Human Rights Watch researchers interviewed more than 90 people about the strikes including witnesses, relatives of those killed, lawyers, human rights defenders, and government officials.
Human Rights Watch reviewed evidence including ordnance and videos from attack sites. Security concerns prevented visits to four of the attack areas.
With rare exceptions, the US government only acknowledged its role in targeted killings in general terms, refusing to take responsibility for individual strikes or provide casualty figures, including civilian deaths.
The Yemeni authorities have been almost as silent. Both governments declined comment on the six strikes that Human Rights Watch investigated.
President Barack Obama describes AQAP, which took responsibility for a botched suicide bombing attempt on a Detroit-bound passenger jet on Christmas Day 2009, as a key threat to US citizens.
The six strikes investigated by Human Rights Watch killed 82 people, at least 57 of them civilians.
Since the September 11, 2001 attacks, the US government has carried out hundreds of targeted killings in Pakistan, Yemen, and Somalia.
In Yemen, the US is estimated to have conducted 81 targeted killing operations, one in 2002 and the rest since 2009.
Research groups report that at least 473 people have been killed in these strikes, the majority of them combatants but many of them civilians.
Human Rights Watch and Amnesty International are jointly calling on the US Congress to fully investigate the cases the two organizations have documented as well as other potentially unlawful strikes, and to disclose any evidence of human rights violations to the public.
The US should investigate attacks that kill civilians and hold those responsible for violations to account," Tayler said.
"It's long past time for the US to assess the legality of its targeted killings, as well as the broader impact of these strikes on civilians," Tayler added.
--ANI (Posted on 22-10-2013)