The SM-3 missile was fired from the USS Lake Erie in the Pacific at about 7:26 PST and collided with the satellite about 130 miles above the ocean, the Pentagon said in a statement.
"Due to the relatively low altitude of the satellite at the time of the engagement, debris will begin to reenter the earth's atmosphere immediately," the statement said. "Nearly all of the debris will burn up on reentry within 24-48 hours and the remaining debris should reenter within 40 days."
"Confirmation that the fuel tank has been fragmented should be available within 24 hours," it added.
However, the Associated Press cited an unnamed defense official close to the situation who said officials monitoring the operation saw what appeared to be an explosion, apparently from the fuel tank.
The Pentagon announced last week that President Bush had decided the Navy would try to shoot down the satellite before it re-entered the Earth's atmosphere because its fuel tank contained approximately 1,000 pounds of hazardous hydrazine.
However, some countries had expressed doubts about the operation, with some such as Russia characterizing the operation as little more than a thinly veiled arms test.