By Mustafa Qadri, Special to CNN

Editor’s note: Mustafa Qadri is Amnesty International’s Pakistan researcher. The views expressed are his own.

It was a sunny October afternoon last year when Mamana Bibi was blown to pieces before her grandchildren’s very eyes. The family matriarch, Mamana Bibi was picking vegetables in the family fields in northwestern Pakistan when a remotely piloted aircraft – or “drone” – used by the United States fired a missile directly toward her, killing Mamana instantly. A second volley of missiles was fired a few minutes later, injuring some of the children who ventured out to where their grandmother had been struck.

Almost a year to the day, the Bibi family’s lives have been torn apart. In a number of in-depth interviews over the last eight months, the family recounted to me how they sold ancestral lands to pay for their injured relatives’ steep medical bills. Mamana’s grief-stricken elderly husband, a respected retired local headmaster, rarely leaves the house. Their grandchildren, including 8-year-old Nabeela, now live in constant fear of the drones, which seem ever present in the skies.

And yet, no one from the U.S. government has even acknowledged the killing, let alone explained why it occurred, apologized or given the family justice or compensation.

The United States claims that its drone strikes are extremely accurate, based on vetted intelligence and that the vast majority of those killed have been linked to al Qaeda and its allies. Yet the world has to take this on faith, since the U.S. administration refuses to disclose key facts, such as details of who is targeted and on what basis. While the Taliban, al Qaeda and other armed groups operate in northwestern Pakistan, it is impossible to fathom how a woman in her 60s surrounded by her grandchildren could be mistaken for a fighter.

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The U.S. drone program has quickly turned into a defining human rights issue for our era. On Tuesday, Amnesty International launched “Will I be next?”: a major report on drone strikes in Pakistan. It is one of the most comprehensive studies ever conducted on this topic from a human rights perspective, based on painstaking research in a dangerous, complex and highly politicized environment.

Amnesty International examined the reported 45 U.S. drone strikes in North Waziristan, the region in Pakistan’s northwestern tribal areas that has seen the most strikes, between January 2012 and August 2013. We conducted detailed field research into nine strikes through interviews with survivors, eyewitnesses, residents and officials, corroborated against satellite imagery, along with video, photographic and audio evidence obtained from strike locations.

Based on all this, it is evident that the drones offer a special kind of misery for people in the tribal areas who live in constant fear of death from the skies. As one local told me: “the fear of drone attacks always exist in the mind of the local people. How can we know that a drone missile may not hit our houses? It can hit anywhere.”

Our research raises serious concerns that the United States may be carrying out unlawful killings in Pakistan, and there is an argument to be made that the attacks could even amount to war crimes or extrajudicial executions. Our report therefore calls for the United States to open up the secretive drone program to public scrutiny and to ensure independent and impartial investigations into strikes that may constitute unlawful killings.

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The reality is that the United States still carries out its so-called targeted killings program in near total secrecy. Successive promises by President Barack Obama and other senior U.S. officials to increase transparency have effectively amounted to a “trust us” approach while the administration continues to withhold basic facts about drone killings and their lawfulness.

North Waziristan and the rest of the tribal areas are neglected and under-developed, and their residents do not enjoy the same human rights protections as the rest of Pakistan. Abuses by the Pakistani military and insurgent groups like the Taliban and al Qaeda are common.

What struck me during our research for this report was the frequency and range of violence endured by people there. Just a few months before I interviewed Mamana Bibi’s family, for example, they were forced to flee their home because the Pakistani military indiscriminately shelled their village in response to a suspected Taliban attack on a nearby checkpoint. Others I interviewed reported receiving threats from unknown men shortly afterwards, possibly by local intelligence services, or fighter groups who have killed dozens of people they suspect of spying for the United States or Pakistan.

While the Pakistani government publicly opposes the U.S. drone program, Amnesty International is concerned that some officials and institutions in Pakistan and in other countries including Australia, Germany and the United Kingdom are assisting the United States to carry out drone strikes that constitute human rights violations.

But the United States and countries assisting its drone program cannot continue to shirk their responsibilities under international law. The secrecy has to end – the facts and legal basis for drone strikes has to be made public, including what rules are in place to protect civilians. And there must be thorough, independent, impartial investigations into all drone strikes that may have resulted in unlawful killings, with those responsible for such killings brought to justice in fair trials. Security concerns – real or perceived – must not be addressed by trampling on the rights of people living in Pakistan.

Earlier this year, President Barack Obama stated in a much-watched speech that decisions made by U.S. government now “will define the type of nation – and world – that we leave to our children.” It’s time for some accountability for these lofty words.