Failed Times Square bomber Faisal Shahzad has said he was driven by anger over dozens of unmanned drone attacks that he witnessed during his most recent five-month visit to his home in Pakistan.
He joins a growing list of homegrown American terror suspects who have cited the escalation of United States military operations on the Afghanistan-Pakistan border in general or in the drone attacks in particular.
They include US resident Najibullah Zazi, the Afghan immigrant who pleaded guilty to a plot to bomb the New York subway system; Major Nidal Malik Hasan, the US-born Army psychiatrist, charged with fatally shooting 13 people at Fort Hood, Texas, last year; and the five American Muslims from Virginia, accused of plotting attacks against targets in Pakistan and Afghanistan.
But there is no sign the Obama administration will ease up in the use of the deadly technology, which is led by the CIA. US officials insist the covert programme has been an effective tool to take out insurgents along the Afghanistan-Pakistan border.
The stepped-up use of drones over the past year has shown no signs of slowing down and was credited this week with the killing inside Pakistan of al Qaeda's third in command.
Al Qaeda acknowledged the death of Mustafa al-Yazid. Reports suggested his wife, three daughters, a grandchild and others died with him.
This week, a senior US official defended the use of drones, saying a careful and rigorous targeting process was used to avoid civilian casualties.
The programme, which officials say has killed hundreds of insurgents in dozens of strikes during the past year, has been condemned by critics who say it may constitute illegal assassinations and violate international law.
They argue intelligence officers conducting the strikes could be at risk of prosecution for murder in other countries.
In a 29-page report released this week, Philip Alston, the independent UN investigator on extrajudicial killings, called on countries to lay out rules and safeguards for carrying out the strikes, publish figures on civilian casualties and prove they have attempted to capture or incapacitate suspects without killing them.
"Unlike a state's armed forces, its intelligence agents do not generally operate within a framework which places appropriate emphasis upon ensuring compliance with international humanitarian law, rendering violations more likely and causing a higher risk of prosecution for war crimes and for violations of the laws of the state in which any killing occurs," wrote Alston, a New York University professor.
The report to the UN Human Rights Council puts unwanted scrutiny on the intelligence operations of the United States, Israel and Russia, who Alston said were all reported to have used drones to kill alleged terrorists and insurgents.
He said the drone strikes launched in Afghanistan, Pakistan and elsewhere were fraught because of the secrecy surrounding them.
Other experts disagree.
"Drone operations are essential," said Bruce Riedel, a former CIA officer and a senior fellow at the Brookings Institution Saban Centre.
"The drones are part of a much broader effort to put pressure on al Qaeda through the war in Afghanistan. They're the cutting edge of the pressure, but they're not the only pressure."
US authorities routinely refuse to talk openly but as criticism has heightened they have slowly begun to respond quietly to the complaints.
"Without discussing or confirming any specific action or programme, this agency's operations unfold within a framework of law and close government oversight," said CIA spokesman George Little.
Administration officials have pointed to a carefully worded speech in March by State Department legal adviser Harold Koh, who said that "US targeting practices, including lethal operations conducted with the use of unmanned aerial vehicles, comply with all applicable law, including the laws of war".
He said the Obama administration was committed to following the law in its operations against terrorists.
The senior US official said the drones used precision targeting and civilian casualties had been overstated.
This view has been challenged by human rights groups and independent observers, who say remotely operated drones risk ingraining a video game mentality about war and can never be as accurate as witness accounts.
"The point is innocent people have been killed, this has been proved over and over again," said Louise Doswald-Beck, a professor of international law at the Geneva Graduate Institute in Switzerland.
"If you don't have enough personnel on the ground, the chances of your having false information is actually quite huge."
Among the most sensitive recommendations in Alston's report is that governments should disclose "the measures in place to provide prompt, thorough, effective, independent and public investigations of alleged violations of law".
Doing so would almost certainly blow open the lid on all manner of secret counterterror operations.
The report also warns CIA personnel could be extradited to those countries where the targeted killing takes place and would not have the same immunity from prosecution as regular soldiers.
Alston claims more than 40 countries now have drone technology.
Doswald-Beck said the next step could be the development of fully autonomous drones and battlefield robots, programmed to identify and kill enemy fighters without human controllers to ensure targets were legitimate.
"If that's the case, you've got a major problem," she said.
FANNING THE FLAMES
In the first four months this year, unmanned Predator drones fired nearly 60 missiles in Pakistan, about the same number as in Afghanistan, the recognised war theatre.
In Pakistan, the pace of drone strikes has increased to two or three a week, up roughly fourfold from the Bush years.
Although drone strikes have killed more than a dozen al Qaeda and Taleban leaders, they have incinerated hundreds of civilians, including women and children.
Predator strikes have inflamed anti-American rage among Afghans and Pakistanis, including first or second generation immigrants in the West, as well as elite members of the security services.