A missile interceptor launched from a Navy warship has struck a dying American spy satellite orbiting 130 miles over the Pacific Ocean, the Pentagon announced late Wednesday.

Officials cautioned that while early information indicated that the interceptor’s “kill vehicle” had hit the satellite, it would be 24 hours before it could be determined whether the fuel tank with 1,000 pounds of toxic hydrazine had been destroyed as planned.

Even so, one official who received a late-night briefing on the mission expressed confidence that the impact had been so powerful that the fuel tank probably had been ruptured.

Completing a mission in which an interceptor designed for missile defense was used for the first time to attack a satellite, the Lake Erie, an Aegis-class cruiser, fired a single missile just before 10:30 pm Eastern time, and the missile hit the satellite as it traveled at more than 17,000 miles per hour, the Pentagon said in its official announcement.

“A network of land-, air-, sea- and spaced-based sensors confirms that the US military intercepted a nonfunctioning National Reconnaissance Office satellite which was in its final orbits before entering the Earth’s atmosphere,” the statement said. By early Wednesday, three Navy warships were in position in the Pacific Ocean to launch the interceptors and to track the mission.

Radar and other tracking equipment, both in space and on the ground, were monitored at Vandenberg Air Force Base, in California, and at a space command headquarters in Colorado Springs, with control of the operation managed by the Strategic Command in Omaha, Neb.

Although the satellite circles the globe every 90 minutes, analysts pinpointed a single overhead pass each day that would offer the best chance of striking the satellite and then having half of the debris fall into the atmosphere in the next three orbits over water or less-populated areas of the Earth.

Defense Secretary Robert M Gates, who left Washington on Wednesday for a week of meetings in Asia, had been empowered by President Bush to issue the order to shoot down the satellite and gave the order several hours before the strike.

The goal of the mission was to prevent the fuel tank from reaching Earth and spilling its hazardous contents in a populous area.