A genetically engineered virus is easier to make and could kill more people than nuclear weapons – and yet no country on Earth is ready for the threat, Bill Gates warned world leaders Saturday.

No one on his panel at the Munich Security Conference argued with him.

“The next epidemic has a good chance of originating on a computer screen,” said Gates, who made a fortune at Microsoft, then spent much of it fighting disease through his global foundation.

Whether “by the work of nature or the hands of a terrorist,” Gates said, an outbreak could kill tens of millions in the near future unless governments begin “to prepare for these epidemics the same way we prepare for war.”

His co-panelists shared some of the same fears.

“Disease and violence are killing fewer people than ever before, but it’s spreading more quickly,” said Erna Solberg, the prime minister of Norway. “We have forgotten how catastrophic those epidemics have been.”

She recalled the Black Death, which she said killed more than half her country’s population and created a 200-year recession in Europe.

“It’s not if, but when these events are going to occur again,” said Peter Salama, executive director of the World Health Organization. “We need to ramp up our preparedness.”

Gates, who founded the Bill & Melinda Gates Foundation with his wife in 2000, has been worrying about the world’s ability to stop a deadly pandemic since Ebola killed thousands two years ago, while governments and militaries struggled to stop it from spreading through West Africa.

“NATO countries participate in joint exercises in which they work out logistics such as how fuel and food will be provided, what language they will speak, and what radio frequencies will be used,” Gates wrote in 2015 in the New England Journal of Medicine. “Few, if any, such measures are in place for response to an epidemic.”

He took the same message to Reddit a year later, when a commenter asked which technologies the world was better off without.

‘”I am concerned about biological tools that could be used by a bioterrorist,” Gates wrote.