These days, there has been an extensive use of unmanned armed vehicles and it has dramatically changed the scenario of modern warfare. Talks are on for building killer robots, which could be programmed to find and kill humans in the battlefield.
Source: Wikia
Source: Motherboard
The emergence of such robots will call the end of the humanity, which is why there are many scientists around the world including Stephen Hawking and Elon Musk who have petitioned to the government of those 40 countries who are actively involved in the development of such killer machines. The potential of the killer machines to work without any human help would pose a serious threat to the protection of civilians across the world. It will also not comply with the international humanitarian law and rights.
Source: Wikia
Source: HumanRightsWatch
The use of autonomous machines for warfare is a huge step that is much beyond the remote-controlled armed drones. These weapons will use much advanced technologies to function. If one country starts to use robots in war against the other countries, the countries will also feel compelled to come out of their peace policies of restraint. This will then lead to a robotic arms race, which can definitely bring havoc to life in this planet. That could probably be the reason why well-known scientists are petitioning against such arms race.
Source: Sploud GIF
The campaign to stop killer robots has the main aim of building public awareness and coverage against the use of robotic arm in military. It is never a practical solution to give the decisions to the machines to kill humans. For these combat robots, the government of the countries of the world should ensure both effective legal control and protection of humans.
Autonomous robots will not be able to judge, help or understand the context of the warfare in any manner, unless they are programmed to have human-like intelligence.