President Barack Obama’s big speech on U.S. counter-terror policy last month promised that drone strikes were “legal,” “heavily constrained” and only carried out if there is “near-certainty that no civilians will be killed or injured.” But the use of the most deadly type of drone attacks calls that rhetoric into question. Known as “signature strikes,” these drone attacks are launched on groups of people who fit the “signature” of militants and terrorists but whose identities are not always known–and they constitute the bulk of strikes carried out in Pakistan, leading to civilian casualties.

Now, a new campaign launched by Brave New Foundation’s War Costs project is looking to expose the impact of “signature strikes” on civilian populations living under the threat of drones. The group has started a petition drive aimed at Congress to demand an end to those types of strikes. Brave New Foundation is partnering with a number of peace and justice groups on the campaign, including Just Foreign Policy, United National Antiwar Coalition, United for Peace and Justice and more.

“Tell Congress to move now to end these signature strikes, save innocent lives, protect America from the blowback of killing innocent civilians, and restore the rule of law,” the petition states. The campaign comes at a moment when some members of Congress are exploring ways to put limits on the Obama administration's use of drone strikes. The administration recently allowed a small number of Congressional officials to look at White House legal memos on drone attacks, though they haven't been released to the public. The Obama administration recently affirmed in a brief that the public has no right to see the Justice Department opinions laying out the legal basis for the drone war.

“Signature strikes,” contrasted with “personality strikes”–strikes that only target individual persons whose identities are known–have wreaked havoc in the Pakistani tribal areas, where America’s Central Intelligence Agency-run drone war continues. An article by McClatchy Newspaper’s Jonathan Landay revealed that “drone operators weren’t always certain who they were killing despite the administration’s guarantees of the accuracy of the CIA’s targeting intelligence and its assertions that civilian casualties have been ‘exceedingly rare.’” The drone war in Pakistan has taken the lives of hundreds of civilians, though the exact number of civilians killed is unknown. The Bureau of Investigative Journalism, a London-based media organization, estimates that 411-884 Pakistani civilians have died as a result of drone attacks, while the New America Foundation puts the numbers at 258-307. At least 178 children in Pakistan and Yemen have been killed by U.S. drones, according to the Bureau of Investigative Journalism.

The Brave New Foundation campaign on “signature strikes” is also paired with a eye-opening video (watch it below) produced by Robert Greenwald, the organization’s founder. (Greenwald sits on the board of the Independent Media Institute, AlterNet’s parent organization.) The video is the result of Greenwald’s first-hand investigation into the impact of America’s drone war on Pakistan.

“In the fall of last year I traveled to Pakistan. Reports of civilian drone casualties were beginning to permeate though American news outlets, prompting myself, and Brave New Foundation, to launch a full-length documentary investigation into the claims coming out of the tribal regions,” he explained in a blog post tied to his campaign.

At the heart of the video is Greenwald’s investigation into a “signature strike” carried out on March 17, 2011 in Datta Khel, an area in the Pakistani tribal region, where America’s drone war is centered. Greenwald interviewed a number of witnesses to the strike–a crucial follow-up to previous reports of mass civilian casualties caused by this specific strike.

The strike targeted a large meeting known as a “jirga” near a bus depot in Datta Khel. “Jirgas,” as they are known in Pashto, the language spoken in the tribal areas, are meetings of tribal members where disputes are hashed out. It is the main judicial structure in tribal areas, and is a key mechanism for stability in tribal areas, as Akbar Ahmed, a former Pakistani Ambassador, told Greenwald.

As witnesses to the strike said, this “jirga” was over a dispute involving a local chromite mine. But 20 minutes after they gathered in the open space for the meeting known to local government officials, four missiles struck the group, killing an estimated 42 people–most of whom were civilians.

Jalal Manzar Khail, a 45-year-old tribal leader, witnessed the aftermath of the strike. In an interview conducted over Skype, he told AlterNet that when he received a message about the drone strike, he “rushed to the scene and when I reached there…there were all the dead bodies in pieces…It was a surprise to me. We were not expecting that the jirga be struck.” The interview was translated by Shahzad Akbar, a Pakistani lawyer who represents many civilian victims of the drone war.

The strike in Datta Khel wiped out tribal leaders, according to Khail. American officials took to the New York Times to claim that the strike targeted “a large group of heavily armed men, some of whom were clearly connected to al Qaeda and all of whom acted in a manner consistent with AQ-linked militants.” But investigations carried out by the Bureau of Investigative Journalism, scholars from New York University and Stanford and Greenwald call the official U.S. account into question. While the Associated Press reported that four Pakistani Taliban fighters were also present since “ they controlled the area and any decision made would need their approval,” Khail said that no Taliban was present. Whatever the case, Greenwald’s and Khail’s account reveal that a large number of civilians were likely killed. A recent New York Times magazine piece quotes some American officials as conceding that that Datta Khel strike was “botched,” though other officials continued to defend the strike.

“There was a great uproar after the strike. Everyone was very angry that the tribal elders had been killed,” said Khail, sitting in a chair wearing a black vest and a white shirt. “This is something they can never forgive or forget what Americans have done to them.”

The drone attack in Datta Khel had wide-ranging repercussions. One survivor showcased in the video, Ahmed Jan, said that he has “severe pain in my ears and also have psychological effects.” The strike also had consequences for the social structure in this tribal area. Khail told AlterNet that as a result of the strike, jirgas don’t take place in public anymore because “they’re fearful that they are in big numbers and they might be targeted.”

And the overall drone strike campaign has led to children not going to school because they are fearful that drones will attack, Khail said. News reports have stated that U.S. drones have attacked madrassas in the past where suspected terrorists were.

Two months after the Datta Khel “signature strike,” Obama counter-terror adviser and current CIA director John Brennan claimed that “there hasn’t been a single collateral death because of the exceptional proficiency, precision of the capabilities we’ve been able to develop.”

Greenwald’s campaign and focus on “signature strikes” like the one that took place in Datta Khel comes as the Obama administration’s deadly drone program continues to command attention. While President Obama’s speech on drones and the U.S. “war on terror” prompted media reports that the drone war was being reined in, the promised new rules purportedly meant to restrict drone use leaves out parts of Pakistan, which is defined as an area of “active hostilities” even though Congress hasn’t explicitly authorized war to be waged in Pakistan. The Obama administration claims the authority to attack the tribal areas in Pakistan because “associated forces” of al-Qaeda reside there. Obama’s speech also didn’t herald the end of “signature strikes” in Pakistan. Instead, the CIA will continue to carry out those strikes in Pakistan, despite questions raised by international law experts as to whether they are legal. Still, the spate of drone attacks in recent months has considerably slowed.

“The Obama Administration has altered its policy towards Pakistan in rhetoric only,” wrote Greenwald in a blog post. “And as long as they continue we will see more strikes like those Datta Khel, and more innocent civilians killed. In doing so they make each of us in United States and Pakistan less safe, and less secure, as we once more attempt to kill our way to security.”

What remains to be seen is the reaction of the new Pakistani government in light of the continued drone attacks. Pakistani officials in the past have decried the campaign at the same time they gave tacit consent to drone strikes. But recently, a Pakistani court ruled that drone strikes are illegal and that Pakistan should use “force” if needed to take down drones. Shahzad Akbar, the Pakistani lawyer who translated the interview with Khail, said he held a June 6 press conference to demand that the new president, Nawaz Sharif, enforce the court ruling.

Sharif said June 5 that “the chapter of daily drone attacks should stop.” The rhetoric could set up a clash with the U.S.–or it could be business as usual, with Pakistani officials criticizing the attacks while giving consent to them, since the drone campaign has also taken out enemies of the Pakistani government.

An American drone attack on Pakistan June 7 allegedly killed nine people. In response, Sharif summoned the U.S. envoy to protest the attack.