From The List of All U.S. Nuclear Weapons:
http://nuclearweaponarchive.org/Usa/Weapons/Allbombs.htmlThe following nuclear weapons have the ability to hit targets beneath the ground.- TYPE: YIELD -- DATE MADE; DESCRIPTION
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- Mk-8*: 25Kt - 30Kt -- Manufactured 11/51 - 5/53; Earth penetrating weapon, gun-assembly HEU bomb, nicknamed "Elsie" (for LC - light case), 2 mods; replaced by the Mk-11
- Mk-11*: 25Kt - 30Kt -- Manufactured 1/56 - 1957; Improved Mk-8 gun-assembly weapon, replaced Mk-8 on 1-for-1 basis; stockpiled as the "Mk-91 penetration bomb"
- Mk-28*: 70Kt - 1.45Mt -- Manufactured 1/58 - 3/58, 8/58 - 5/66; Multipurpose TN tactical and strategic bomb; longest weapon design in U.S. (33 years); 2nd largest production run of any U.S. weapon design; Y4 was fission only; 20 mods and variants; replaced by B-61 and B-83 bombs; 1-point safety problem with primary discovered after start of initial manufacture, halting production for 5 months
- W-30*: 300T, 500T, 4.7Kt, 19Kt manufactured 2/59 - 1/65 Multipurpose warhead: Talos SAM/SSM, XW-30-X1 TADM (Tactical Atomic Demolition Munition) warhead; Talos - 1 yield, 3 mods; TADM - 2 yields stockpiled
- W-45*: 500 T; 1Kt, 5Kt, 8Kt, 10Kt, 15Kt - manufactured 4/62 - 1984, retired 7/67 - 9/88, 750 produced; Multipurpose UCRL designed tactical warhead; small implosion design;
- Mk-54*: 10T - 1Kt - Manufactured 8/64 - 6/66; M-129/M-159 SADM (Special Atomic Demolition Munition) used a Mk-54 warhead package very similar to Davy Crockett; 2 mods; mechanical combination lock PAL
- Mk-57*: 5Kt - 20Kt - Manufactured 1/63 - 5/67; Light weight multipurpose tactical strike/depth bomb; boosted implosion fission weapon; modular design, 6 mods; PAL B; 1x12.5 ft ribbon parachute; Retired in favor of B-61
- MK/B-61: 0.3Kt - 340 Kt; Manufactured 10/66 - early 90s; Multipurpose tactical/strategic bomb; basic design adapted to many other weapon systems; 4 yields; 11 mods, 5 in service; PAL B, D, F; uses IHE in primary; parachute: 1x17 ft or 1x24 ft ribbon; longest production run of any U.S. nuclear weapon, oldest design in service; part of the U.S. "enduring stockpile"
- B-83: low Kt to 1.2 Mt Manufactured 6/83 - 1991; Current high-yield strategic TN bomb; PAL D; uses IHE, fire resisitant pit; parachutes: 3x4 ft, 1x46 ft; 1x5 ft, 1x46 ft
- W-86: Canceled Sept 1980 Earth penetrating warhead for the Pershing II SSM, canceled due to change in mission from hard to soft targets
- B 90: 200 Kt Canceled 1991 USN nuclear strike/depth bomb; intended to replace Mk-57; PAL D; 1x26 ft parachute
- W-91: 10Kt, 100Kt Canceled Sept 1991 SRAM-T (short range attack missile - tactical) warhead; SRAM-T was a SRAM II derivative for the F-15E Eagle fighter/bomber; LASL TN design orignally called "New Mexico 1"; safety features: FRP, IHE; 2 yields
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A * indicates a retired weapon.
As you can see, we've had bunker-busting Nukes for some time. Most likely weapon to be used against Iran: The MK/B-61. This WMD has bunker-busting capabilities and can have it's yield set anywhere between 0.3Kt and 350Kt. Of course, if the DoD has made some new monstrosity not listed above, then Bush would have that as an option as well.
More about the MK/B-61 here:
http://en.wikipedia.org/wiki/B-61 and here:
http://www.brook.edu/FP/PROJECTS/NUCWCOST/lasg.htmFrom the second link, a few highlights:
A central and expressed purpose of the Comprehensive Test Ban Treaty (CTBT) has always been to arrest the further evolution of the world's nuclear arsenals. This modified weapon? certified without nuclear testing and deployed after signing the CTBT?undercuts that treaty and could provide political cover to countries which have their own unsatisfied nuclear ambitions.
Earth-penetrating weapons, deployed by the Clinton adminstration in the post-Cold-War era, were rejected for deployment by Presidents Carter, Reagan, and Bush. What is the new reason to deploy these weapons? What are the new targets? What is known about the B61-11 strongly suggests that its rushed development has been motivated by a desire to target one or more non-nuclear-weapon states.
On July 8, 1996, the International Court of Justice ruled that any use or threat of use of nuclear weapons, other than possibly in the case where the very survival of a nation was threatened, was against international law. After this landmark decision, it is difficult to legally support the deployment, let alone the new development, of any tactical nuclear weapon? especially one whose development appears to have been motivated by a desire to target non-nuclear weapon states.