big MAD type nukes are useless in today's context... even the
USA is developing a new class of "sub-yield" warheads that can
neutralise hard-targets like bunkers.
there are also new bomb designs that minimises fallout. the
radiation will dissipate within a relatively short time, compared
to the tens of thousands of years for old-type warheads.
we don't need to get one of those 100kton warheads to have a
deterrent.
if even al qaeda was rumoured to have acquired "briefcase nukes",
then hypothetically, a nuke that sized, placed either on an f16 or
a missile dropped on putrajaya would very well prove the point
already.
and under the UN charter, a country CAN legally drop a nuke on a
bellgerent aggressor if it believes that its existence is in peril.
that is what keeps israel's deterrent alive.