The Israelis, all by themselves can stop Iran from getting nukes. Not saying it would be an easy or popular thing to do...but it can be done. I gave my thoughts re this in a thread about 2 weeks ago.
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The Iranian installations that are in bunkers are what really need destroying to stop their nuclear program.
Nuclear bunker busters might be used, but even a 400kt device like our B61-11 might have difficulty penetrating to a sufficient depth to contain the blast and thus prevent massive fallout when the blast breached the surface and spewed many tons of radioactive debris into the sky. And although a 400kt or even 1 megaton warhead is a very powerful thing...it is quite weak underground when the target for destruction is a fortified bunker. It would be the shock wave that would need to destroy the bunker and for that a 400kt device would need to detonate very close to the bunker, perhaps as close as 400-700 feet. The problem is that even though you know where the entrances to the bunker are the actual bunker might be anywhere within a mile or so from those entrances. This means you would need to somehow get a precise location of the bunker by placement of seismic sensors ahead of time (listening for the sounds from industrial machinery and determining where the sound originates from)
A much more promising attack would be to destroy all the entrances and exits to such an installation and then control the area for an extended time.
The actual installation itself would remain intact unless a fool had designed it poorly. The engineers and workers would soon be dead, but the equipment would remain untouched.
To hold such an area from the types of assaults the Iranians could bring to bear would require creating your own underground fortifications near the entrances to the bunker.
Massive mine laying would be required to protect against human-wave attacks such as were used in the Iran/Iraq war.
Iranian missile attacks would be totally ineffective against even hastily made Israeli underground defenses and could be dismissed as a real threat.
Chem/biological weapons would be used and so preparations would need to be made for protection.
It might in extreme circumstances be necessary to use neutron weapons to keep attacking forces at bay... this would require the Israelis to first actually possess such weapons (likely) and be willing to use them in extreme circumstances (also likely), they would also need to be able to protect themselves from the heavy neutron bombardment...this can be done but is not an easy thing to engineer quickly in the field so preparation would need to be underway immediately upon taking control of the area.
The neutron weapons would be able to immediately incapacitate attackers (even inside tanks) inside a blast radius of about 1/3 mile with a radiation dose of roughly 80 Gy...after such a dose only a very few ‘walking deadmen’ would be able to remain active, and those for a very short time.
The small radiation weapons would release the force of about 1kt compared to a conventional nuclear weapon...this is a very small yield and would pose no threat at all to Israeli soldiers in even rudimentary underground shelter.
The Israeli force would need to be supplied with food and other essentials for a possible extended time...long enough to locate and destroy the Iranian underground installation by tunneling and then placing appropriate charges.
This would certainly call for a dedicated force of extraordinary men....but such men do exist and I’m certain Israel has enough of them to do the job.
I thought that the location of the bunkers were known. That would explain why the Israelis have held off for so long.