1.   Vital strategic sites, such as fields of missile silos, would be protected by ground-based systems, which would hit incoming warheads.

2.   A diagram in the paper shows the Russian concept of a mobile land-based system that would be cued by satellites and would destroy incoming warheads.

3.   Empty silos which contained Spring interceptors, designed to destroy incoming warheads, in the abandoned Safeguard antimissile base.

4.   For one thing, the technology to destroy even a handful of incoming warheads in outer space remains elusive.

5.   In the three tests so far, the interceptor twice missed the mock incoming warhead and produced one partial success.

6.   Instead of guiding itself to a collision with the incoming mock warhead in midflight, it missed.

7.   Instead, both prototype weapons simply flew past mock targets in space, trying to distinguish incoming warheads from decoys.

8.   It might rely on tactical nuclear missiles fired at incoming warheads, thus introducing a new class of warheads.

9.   Rumsfeld owes the country a rigorous research and testing program to establish whether any of the proposed approaches can reliably evade decoys and destroy an incoming warhead.

10.   Several leading missile scientists contend that the defensive system now being tested by the Pentagon may not be able to distinguish between decoys and an actual incoming nuclear warhead.