New evidence indicates that the U.S. has carried out unlawful killings in Pakistan through drone attacks, some of which could even amount to war crimes, Amnesty International said in a major new report released Tuesday, Oct 22.

The report, “’Will I be next?’ U.S. drone strikes in Pakistan”, is one of the most comprehensive studies to date of the U.S. drone program from a human rights perspective. It documents recent killings in Pakistan’s northwestern tribal areas and the almost complete absence of transparency around the U.S. drone program.

“Secrecy surrounding the drones program gives the U.S. administration a license to kill beyond the reach of the courts or basic standards of international law. It’s time for the USA to come clean about the drones program and hold those responsible for these violations to account,” said Mustafa Qadri, Amnesty International’s Pakistan Researcher.

Amnesty International reviewed all 45 known drone strikes that took place in North Waziristan in northwestern Pakistan between January 2012 and August 2013. The region that has seen more strikes than any other part of the country.

The organization conducted detailed field research into nine of these strikes, with the report documenting killings, which raise serious questions about violations of international law that could amount to war crimes or extrajudicial executions, AI said.

“We cannot find any justification for these killings. There are genuine threats to the USA and its allies in the region, and drone strikes may be lawful in some circumstances. But it is hard to believe that a group of labourers, or an elderly woman surrounded by her grandchildren, were endangering anyone at all, let alone posing an imminent threat to the United States,” said Qadri.

The report was released in a joint news conference with Human Rights Watch, which issued its own report on drone and other air strikes in Yemen.

The U.S. Joint Special Operations Command (JSOC), which is a semi-covert arm of the military, and the Central Intelligence Agency (CIA) are estimated by research groups to have carried out 81 targeted killing operations in Yemen: one in 2002 and the rest since 2009. The strikes by drones, warplanes or cruise missiles by various counts have killed at least 473 combatants and civilians, the 97-page report says.

After many years of neither confirming nor denying such strikes, President Obama and other top U.S. officials began publicly acknowledging the targeted killings program in 2010. However, citing national security concerns, the administration has provided only the barest information about individual strikes. For example, U.S. authorities have not revealed the number of strikes, the number of civilians and alleged combatants killed or wounded, or, with a few exceptions, the target of the strikes. Moreover, the administration’s legal rationale for such killings, outlined in various speeches and “fact sheets” by the government in the past two years, has been inadequate, the report says.

Amnesty International and Human Rights Watch are jointly calling on the U.S. Congress to fully investigate the cases the two organizations have documented and other potentially unlawful deaths, and to disclose any evidence of human rights violations to the public.