The US plans to shoot down a disabled spy satellite before it enters the earth's atmosphere.
President George W Bush opted for a plan to have the Navy shoot the 2,270kg minivan-size satellite with a missile, after security advisers suggested its reentry could lead to a loss of life.
Military officials hope to strike the satellite just before it reaches the atmosphere and drive it into ocean waters.
Thousands of space objects fall to Earth each year, but they generally scatter over a huge area and there have never been any reported injuries.
'What makes this case is a little bit different...was the likelihood that the satellite upon descent to the Earth's surface could release much of its 54kg of its hydrazine fuel as a toxic gas,' said James Jeffries, deputy national security advisor.
He told a Pentagon briefing that the satellite was unlikely to hit a populated area and described the danger of toxic gas as limited.
But Mr Jeffries added 'There was enough of a risk for the president to be quite concerned about human life.'
The satellite, known as L-21, has been out of touch since shortly after reaching its low-Earth orbit. The satellite has fallen more than 70 km to an orbit at around 280 km above the Earth.
