More than 100 of the world’s largest technology, cybersecurity and financial companies have issued an unusual warning: The rapid development of artificial intelligence could trigger a new wave of advanced cyberattacks against critical infrastructure within the coming months, including hospitals, water facilities and internet infrastructure. In an open letter signed by companies including Microsoft, Google, OpenAI, Amazon and Anthropic, the firms warn that advanced AI tools are rapidly lowering the threshold required to carry out complex cyberattacks. Capabilities that once required extensive expertise, time and resources could become far cheaper, faster and more accessible even to less sophisticated attackers. According to the companies, the window of opportunity is closing. As AI models continue to improve, so does their ability to identify vulnerabilities, write code and autonomously carry out increasingly large parts of an attack chain. They are therefore calling on governments and companies to begin significantly upgrading their defenses now, rather than wait until such capabilities become even more widespread. Notably absent from the list of signatories are Meta and Elon Musk’s xAI. An attack that once took weeks could be reduced to minutes One of the main concerns involves what are known as “agentic” attacks — attacks in which AI systems do not merely provide answers or write code, but can independently carry out a sequence of actions to achieve a goal. In the letter, the companies warn that AI agents can operate at machine speed, search systems for vulnerabilities, adapt their actions to what they find and move on to the next stage with almost no human intervention. As a result, an attack process that once might have taken days or weeks could, at least in some scenarios, be reduced to minutes. The problem, they argue, is that the computer systems of many organizations are simply not prepared