Law enforcement, emergency response and border control agencies have won greater access to the nation's spy satellites and other sensors to monitor U.S. territory.

The sharing of imagery and data will be especially useful in policing land and sea borders and in disaster planning, Charles Allen, the Department of Homeland Security's chief intelligence officer, said in a phone interview Wednesday.

The effort may eventually support domestic law enforcement activities as well, he said, but the legal guidelines for that are still being worked out.

At least 11 domestic agencies have had access to limited amounts of spy satellite imagery for the last 30 years, mostly on a case-by-case basis.

Such imagery has been used to monitor national disasters such as Hurricane Katrina. It also could be used to map evacuation routes prior to anticipated disasters, or to identify patterns of illegal movement across borders.

The CIA and Pentagon are generally prohibited from spying on American citizens, and Allen stressed that the new data-sharing effort doesn't violate that ban. "This is not a system for tracking Americans," Allen said.

A new office within the Department of Homeland Security, called the National Applications Office, will now be the conduit for all domestic requests for spy satellite information.

It will be up to the intelligence agencies themselves — the Pentagon's National Geospatial Intelligence Agency, for example — to determine which requests they can honor.

Many imagery satellites are in low-Earth orbit, passing over the United States periodically on their way to covering foreign targets. They can easily be directed to photograph U.S. locations as they pass overhead.

But collecting the data is just a small part of the task. The data or imagery must then be analyzed — turned into a useable product — and disseminated.

Analysts across the intelligence community are already swamped with incoming data from foreign surveillance, and they may have little time for lower-priority work.

"That will be a challenge," Allen said. "In many cases they will be able" to satisfy the request. "In some cases they won't."

The new effort, first reported Wednesday by the Wall Street Journal, largely follows the recommendations outlined by a 2005 independent study group headed by Keith Hall, a former chief of the National Reconnaissance Office and now vice president of the consulting firm Booz Allen Hamilton.

Allen said Wednesday that the U.S. Geologic Survey has some analysis capabilities that will be tapped to support domestic users.

Exactly how useful low-Earth orbit satellites will be to domestic government users is a central question, said John Pike, a space expert and director of GlobalSecurity.org.

"It's not immediately apparent to me the satellites would tell me something I couldn't otherwise learn from an airplane," Pike said.

Spy satellite resolution, while better than that offered by commercial suppliers like Google Earth, is not precise enough to track individuals, and can photograph a given target only at intervals.

"There are much better ways of surveilling an individual than using a satellite to do so," Hall said. "Satellite capability, while quite impressive, (is) not of a kind that allows you to spy on an individual. You can monitor activity periodically, but you can't tell who you are looking at."

Using spy satellites to capture data about the United States also raises privacy concerns.

"What could go wrong? There's the possibility of a recurrence of past abuses — surveillance used against political opponents as in the Civil Rights era, the McCarthy era," said Steven Aftergood, director of the Project on Government Secrecy at the Federation of American Scientists.

"There's also an incidental erosion of personal privacy in which one now has to assume that anywhere you are, you are subject to overhead surveillance by the government. And that is a change in what it means to be an American," Aftergood said.

Allen said the office's operations will be monitored closely by oversight committees, inspectors general, and DHS' privacy office.

"This is going be a very controlled process and I can't conceive of Americans having any serious concern," Allen said. "No American should be at all concerned."

Still, Aftergood advised caution, citing Congress' recent embrace of new wiretapping powers for the government.

"They need to be subjected to an appropriate level of oversight. We seem to be retreating from intelligence oversight, not improving it," he said. "The adoption of intelligence technology is moving faster than oversight can keep up with.... The basic system of checks and balances is being overtaken by new technology."