Despite no official confirmation by the Pentagon, it's a very safe assumption that the US created the Stuxnet worm (with Israel's help) to take Iran's nuclear reactors offline. But when it was first discovered, it seemed too sophisticated for Earthlings.
NPR spoke with German security expert Ralph Langner, who was the first in the world to discover Stuxnet whirling around in the wild. It was the most amazing digital weapon he'd ever seen. And he knew that something so powerful could only really come from one place: "Thinking about it for another minute, if it's not aliens, it's got to be the United States," Langner concluded.
Right now, the US likely has the lead in the ability to both cook up and deploy an online attack with offline damages. But it won't stay that way for long—and we know it. That's why the military's slowly ringing the alarm bells already.