The head of a US intelligence agency told the Associated Press that commercial satellite services like Google Earth may need to be censored in the future in order to protect American interests.

Vice Admiral Robert Murrett, who heads the National Geospatial-Intelligence Agency, spends his days helping the government map the planet and studying imagery. Once the exclusive domain of the government, commercial satellite imagery has attained high-enough resolutions that the government is thinking about ways to restrict its use in times of war or other emergency situations.

"If there was a situation where any imagery products were being used by adversaries to kill Americans, I think we should act," he said in the interview. "I think we may need to have some control over things that are disseminated. I don't know if that means buying up all the imagery or not. I think there are probably some other ways you can do it."

The reference to "buying up all the imagery" refers to the government's practice of purchasing all commercially-available satellite data on Afghanistan during the early days of the conflict there. While buying up all available images may be one solution to the problem, the government may also be able to exert a different kind of pressure, as it provides nearly $1 billion in grants to major US imagery firms.

As the imagery market becomes international, though, the competing demands of local governments may be more difficult to sort out. The issue is already becoming tricky for companies like Google that offer popular products using satellite imagery. Google has already faced requests from Vice President Cheney to remove images of his residence and from the Indian government to blur sensitive military sites. Headlines in the UK have already claimed that Iraqi insurgents are using Google Earth to attack British troops.

Certain disruptive technologies (peer-to-peer file sharing comes to mind) are difficult to stuff back inside the bag once they've been unleashed on the world, and and satellite mapping may someday be one of them. For now, though, the number of commercial satellites is still quite limited, and the companies that do the mapping well are few in number. As that changes, the US government—and all other governments—will find it harder and harder to control the information that is produced.