Washington ? Deferring to Secret Service worries about terrorists, the government is deliberately blurring its highest-quality aerial photographs over Washington to hide objects in plain view on the roofs of the White House, Capitol and Treasury Department.

The government also obscured aerial views of the Naval Observatory compound where Vice President Dick Cheney lives. It made no effort to blur detailed photographs showing the Pentagon, Supreme Court, CIA headquarters, Justice Department or FBI headquarters.

Experts said they feared the unusual decision reflected a troublesome move toward new government limits on commercial satellite and aerial photography, a booming industry driven by recent technology advances that includes some major companies based outside the United States.

Some commercial satellites already can snap photographs almost as detailed as images shot from airplanes that were ordered blurred by the government.

Experts also questioned the effectiveness of blurring one set of government-financed photographs. Tourists can see the roofs of the White House and U.S. Capitol from dozens of tall buildings downtown, and the Web site for the National Park Service shows a June 2002 photograph of the White House from atop the Washington Monument.

“We have to accept that we’re not going to be invisible from space anymore,” said James Lewis, a satellites expert for the Washington-based Center for Strategic and International Studies. “The knee-jerk reaction is to turn it off. Once in a while that makes sense, but not very often.”

Secret Service spokesman John Gill said the agency worried that the high-altitude photographs, so detailed that pedestrians can be seen in crosswalks, “may expose security operations.”

The affected images include:

l The White House, where the roof is obscured to hide objects in plain view.

l The nearby Old Executive Office Building where many presidential aides work. The roof on that photo is obscured and interior courtyards blurred.