In 2007 China conducted an anti-satellite (ASAT) test, shattering an aging Chinese weather satellite
with a missile. This led to the creation of over 3,000 new debris fragments--all potentially catastrophe-causing should they collide with a shuttle or space station.
But surprisingly, for debris at low altitudes, fragmentation by ASAT device can actually be helpful in speeding orbital decay
. In February of 2008, the United States used an ASAT interceptor to destroy a failed satellite at an altitude of 150 miles (compared to 537 miles for the China test). Because of greater atmospheric drag at that altitude, 99 percent of the debris re-entered the atmosphere within one week (and burned up on re-entry). While controversial, this technique can still be used to remove defunct satellites from Low Earth Orbit at altitudes below 180 miles.
As this remarkably detailed painting
illustrates, ASAT weapons are very destructive. Some space agencies are pushing for an outright ban at high altitudes.