Scientists trained AI to create chemical weapons Source: (https://go.nature.com/3ik58O4) The thought had never previously struck us. We were vaguely aware of security concerns around work with pathogens or toxic chemicals, but that did not relate to us; we primarily operate in a virtual setting. Our work is rooted in building machine learning models for therapeutic and toxic targets to better assist in the design of new molecules for drug discovery. We have spent decades using computers and AI to improve human healthnot to degrade it. We were naive in thinking about the potential misuse of our trade, as our aim had always been to avoid molecular features that could interfere with the many different classes of proteins essential to human life. Even our projects on Ebola and neurotoxins, which could have sparked thoughts about the potential negative implications of our machine learning models, had not set our alarm bells ringing. Our companyCollaborations Pharmaceuticals, Inc.had recently published computational machine learning models for toxicity prediction in different areas, and, in developing our presentation to the Spiez meeting, we opted to explore how AI could be used to design toxic molecules. It was a thought exercise we had not considered before that ultimately evolved into a computational proof of concept for making biochemical weapons. ..... Our toxicity models were originally created for use in avoiding toxicity, enabling us to better virtually screen molecules (for pharmaceutical and consumer product applications) before ultimately confirming their toxicity through in vitro testing. The inverse, however, has always been true: the better we can predict toxicity, the better we can steer our generative model to design new molecules in a region of chemical space populated by predominantly lethal molecules. We did not assess the virtual molecules for synthesizability or explore how to make them with retrosynthesis software. For both of these processes, commercial and open-source software is readily available that can be easily plugged into the de novo design process of new molecules7. We also did not physically synthesize any of the molecules; but with a global array of hundreds of commercial companies offering chemical synthesis, that is not necessarily a very big step, and this area is poorly regulated, with few if any checks to prevent the synthesis of new, extremely toxic agents that could potentially be used as chemical weapons. Importantly, we had a human in the loop with a firm moral and ethical dont-go-there voice to intervene. But what if the human were removed or replaced with a bad actor? With current breakthroughs and research into autonomous synthesis, a complete designmaketest cycle applicable to making not only drugs, but toxins, is within reach. Our proof of concept thus highlights how a nonhuman autonomous creator of a deadly chemical weapon is entirely feasible.