The Vatican joins the international call against killer robots

Leo XIV’s first encyclical rejected the idea that algorithms and autonomous systems can make lethal decisions and called for global regulations to guarantee human control over the use of force.

On May 25, Pope Leo XIV published his first encyclical, which offers a critique of artificial intelligence. In Magnifica Humanitas (Magnificent Humanity), the pontiff warned about the risks of delegating fundamental human decisions to automated systems, especially in military contexts.

The document argues that the development of artificial intelligence must be accompanied by clear ethical criteria. Among these points, there is growing concern about the use of AI in armed conflicts and about the development of weapons systems capable of operating with different levels of autonomy.

In the words of Leo XIV, “decisions concerning the use of lethal force must remain under effective human control and cannot be left in the hands of automated mechanisms or processes whose logic is inaccessible to those who use them.”

This is not new, however: the Vatican had already raised these challenges regarding the use of autonomous weapons systems and AI. During the papacy of Francis, in 2024, the then leader of the Catholic Church stated that “no machine should ever have the capacity to decide over a person’s life.” 

Both Francis and Leo XIV consider that handing life-or-death decisions over to algorithms poses a fundamental ethical problem because it dilutes human responsibility and distances political and military leaders from the consequences of their actions.

However, these concerns are not exclusive to the Catholic Church. In 2023, representatives of various Christian, Muslim and Buddhist religious organizations signed a joint declaration demanding urgent action to prevent the development and deployment of so-called “killer robots”.

The Stop Killer Robots campaign works along the same lines: an international coalition driven in part by Human Rights Watch (HRW) since 2013, the initiative calls for an international treaty establishing prohibitions and regulations for autonomous weapons systems.

Pope Leo XIV further added that responsibility for the development and use of artificial intelligence must be clearly defined at every stage of the process, from those who design these tools to those who use them in concrete situations. For the pontiff, any military application of AI must be subject to the highest ethical standards and respect human dignity.

The debate is also taking place at the United Nations. In June, member states will, for the first time, formally examine the opportunities and risks associated with the military use of artificial intelligence. In November, they will meet again in Geneva to discuss the possible opening of negotiations aimed at drafting an international instrument to regulate these technologies.

So far, 130 countries have expressed support for some kind of legally binding framework on these weapons. As calls grow to limit the military use of artificial intelligence, human rights organizations are also warning about other impacts associated with this technology, from the massive consumption of natural resources to the use of personal data without consent.

Environmental impact and human rights

As discussions grow over the military use of artificial intelligence, various organizations are also warning about its environmental and social consequences.

Amnesty International warned that the expansion of generative artificial intelligence requires ever more technological infrastructure, which translates into greater demand for energy, water and computing capacity. The growth of large AI models requires large-scale data centers and computer systems with high levels of energy consumption.

According to the organization, this process also has concrete impacts on local communities. In some cases, data centers are built in areas affected by water or electricity shortages, creating tensions among the populations living in those areas.

Various organizations point out that this concern is also reflected in the sustainability reports of the tech companies themselves. Along these lines, Google reported that its greenhouse gas emissions increased by 48% between 2019 and 2024, while Microsoft reported a 29% increase between 2020 and 2024. Both companies link part of that growth to the expansion of data centers and the needs associated with developing artificial intelligence.

Communities in countries such as Chile, Mexico and the United States have also voiced their opposition to new technology infrastructure projects because of the impact they could have on natural resources.

Amnesty International also questioned the way in which several companies develop their artificial intelligence systems. The organization warns that many models are trained on the massive collection of information available on the internet, without the consent of the people whose data is used.

In light of this situation, Amnesty called on states to move forward with regulations that guarantee the protection of human rights and hold tech companies accountable for the potential impacts of their business and design decisions.