By a vote of 387-36, the House of Representatives passed a
spending bill on Tuesday that contains $7.5
million to research the so-called "Robust
Nuclear Earth Penetrator".
One Energy Department official said the device
"would enhance the nation's ability to hold hard and deeply
buried targets at risk".
The Senate approved the measure by voice vote soon after.
It will now go to President George Bush for signature.
Bunker-busters
US scientists are looking into the possibility of converting
into bunker-busters two existing warheads - the B61 and the B83,
according to Bush administration officials.
The B61, which has selectable yields ranging from 0.3 kilotonnes
to 300 kilotonnes, is a tactical thermonuclear gravity bomb that can
be delivered by strategic as well as tactical aircraft
.
The B83, whose yields range from one to two megatonnes, is
designed for precision delivery from very low altitudes, most likely
by B-2 stealth bombers, military experts said.
It has a nose cone
capable of withstanding a supersonic-speed collision with concrete
or steel and a delayed detonation to allow the aircraft to escape
the blast.
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Bush had requested $15m for
nuclear research |
High-precision strikes
The main task now is to find a way of hardening these bombs'
shells to allow them to survive penetration through layers of rock,
steel and concrete before detonating close to their deep underground
targets.
But the $7.5 million allocated for the penetrator represents a
50% reduction from the $15 million requested by the
administration.
An additional $6 million has been earmarked to study
low-yield nuclear weapons that some experts believe could be useful
in high-precision strikes.
Experts say that a five-kilotonne nuclear
explosive detonated, for example, right on a missile silo door will
vaporise the door as well as the missile inside.
Underground targets
Low-yield weapons could also be effective against other types of
underground facilities such as command posts and hardened ammunition
dumps.
According to the Defense Intelligence Agency, at least 10,000
such bunkers currently exist in over 70 countries around the world.
More than 1400 of them are used as strategic storage sites for
weapons of mass destruction, concealed launch pads for ballistic
missiles as well as leadership or top-echelon command and control
posts.