The US has successfully hit a disabled spy satellite with a missile fired by a warship.
Contact with USA 193, believed to be a radar imaging reconnaissance satellite, was lost shortly after its launch in December 2006.
The US Department of Defence (DoD) opted to shoot down the satellite before it re-entered the earth's atmosphere due to a large quantity of hydrazine fuel on board.
The fuel, believed to be frozen, would survive the heat of re-entry and could leak toxic gas over a wide area, harming or killing people if inhaled, the DoD says.
The satellite was hit by a SM-3 missile fired from a warship near Hawaii, at a distance of 130 miles.
It is not yet known if the fuel tank was ruptured.
Remains of the satellite are expected to begin to fall to earth immediately, with 25 percent expected to survive re-entry, US officials say.
The mission has been criticised by China and Russia, who say it is a cover for the testing of an anti-satellite weapon.
China carried out such a test last year, prompting fears of a space arms race.
Russia says spacecraft have crashed to earth in the past, many with toxic fuel on board, but had never merited such "extraordinary measures".
By Elizabeth Clifford-Marsh