The U.S. military says the North American Aerospace Defense Command, the FAA and other law enforcement and intelligence organizations are reviewing sensor data and reviewing what happened when a gyrocopter landed on the lawn of the U.S. Capitol.

A NORAD spokesman says the incident highlights a persistent vulnerability: the inability to detect some low, slow-flying objects. But he says the military has begun a three-year test of a radar blimp in the region.

The Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System has been placed in orbit over Aberdeen Proving Ground in Maryland. It includes a football field-sized airship that floats at about 10,000 feet.

Officials expect it to be integrated into the air defense system in a few months.

(AP)