The predator drone - an unmanned aerial vehicle (UAV) - is one of the relatively new lethal weapons used by the United States for targeted killings of suspected terrorists, particularly in Pakistan, Afghanistan, Yemen and Somalia.
And since it is unmanned and remotely controlled, the drone does not risk the lives of U.S. soldiers.
But the weapon has increasingly come under fire because of the collateral damage in the spillover killings of innocent civilians, including women and children.
On Monday, a report jointly published by Human Rights Watch (HRW) and Harvard Law School's International Human Rights Clinic (IHRC) has warned of an even more deadly weapon: killer robots.
Described as fully autonomous, these weapons will have the capability to select and fire on targets without human intervention in future wars.
The primary concern of HRW and IHRC is the impact fully autonomous weapons would have on the protection of civilians during times of war.
In the report released Monday, they called on governments to pre-emptively ban these yet-to-be deployed weapons because of the danger they pose to civilians in armed conflict.
Asked how feasible it was to garner support at the United Nations for an international convention to ban such killer robots, Steve Goose, arms division director at Human Rights Watch, told IPS that many governments are not yet aware of the status of development of, and plans to produce fully autonomous weapons systems.
So, a good deal of education needs to be done, he said.
"But we are convinced that the obvious and undeniable inconsistency of these future weapons with existing international humanitarian law, and the degree to which they will be repugnant to the public conscience, will make an international prohibition on killer robots achievable in the near term," said Goose.
Asked how drones differ from fully autonomous weapons, Goose said drones have a "man in the loop" - a human has remote control, a human selects the target and decides when to fire the weapon.
The 50-page report titled "Losing Humanity: The Case Against Killer Robots" expresses concern over these fully autonomous weapons, which would inherently lack human qualities that provide legal and non-legal cheques on the killing of civilians.
In addition, the obstacles to holding anyone accountable for harm caused by the weapons would weaken the law's power to deter future violations.
"Giving machines the power to decide who lives and dies on the battlefield would take technology too far," said Goose, pointing out that human control of robotic warfare is essential to minimising civilian deaths and injuries.
Fully autonomous weapons do not yet exist, and major powers, including the United States, have not made a decision to deploy them, according to the report. However, the most high-tech militaries are developing or have already deployed precursors that illustrate the push toward greater autonomy for machines on the battlefield, it said.
The United States is a leader in the technological development of killer robots, while several other countries, including China, Germany, Israel, South Korea, Russia, and the United Kingdom have also been involved.
"Many experts predict that full autonomy for weapons could be achieved in 20 to 30 years, and some think even sooner," HRW said.
Both HRW and IHRC Monday called for an international treaty that would absolutely prohibit the development, production, and use of fully autonomous weapons.
They also called on individual nations to pass laws and adopt policies as important measures to prevent development, production, and use of such weapons at the domestic level.
Asked what weapons are currently banned under international conventions, Goose told IPS that banned weapons include poison gas, chemical and biological weapons, blinding lasers, antipersonnel mines, and cluster munitions.
The 1995 ban on blinding lasers (spearheaded by the International Committee of the Red Cross and Human Rights Watch) is a key example of banning a weapon before it was widely produced or fielded by armed forces - a preemptive ban such as HRW and others are aiming for with fully autonomous weapons, Goose said.
The report analyses whether the technology would comply with international humanitarian law and preserve other cheques on the killing of civilians.
But it finds that fully autonomous weapons would not only be unable to meet legal standards but would also undermine essential non-legal safeguards for civilians.
"Our research and analysis strongly conclude that fully autonomous weapons should be banned and that governments should urgently pursue that end," the report says.
