|I think the nuclear disarmament movement ought to concentrate on banning these non-strategic nuclear weapons completely. They provide a slippery slope for escalation of a non-nuclear war into a nuclear one and it is difficult to argue that they are necessary for deterrence, which is accomplished by strategic nuclear weapons anyway. In order to be usable, the authority to launch tactical nuclear weapons needs to be more devolved than with strategic ones, which makes them even more dangerous as there are more opportunities for a rogue or a mistaken launch. The U.S. wisely dismantled its last nuclear artillery shell a couple of months ago and other nuclear powers need to follow suit. The same needs to be done with tactical nuclear rockets/missiles, nuclear demolition munitions, tactical nuclear bombs and other such nuclear devices that are not strategic in nature. Because strategic deterrence would not be directly effected by this ban, I think it could be feasible that the current nuclear powers would agree on the matter, though U.S. would have to abandon any plans to field bunker-buster nukes, mini-nukes, micro-nukes and similar nuclear contraptions that it is currently exploring.
There are two main problems I can see with this. One is a matter of definition of non-strategic (battlefield, tactical, theater and other operational) nuclear weapons as opposed to strategic ones. I would advocate a two-tiered definition:
1) Any warhead with a yield of 20 kilotons or less including warheads with variable yield that can be set for an explosion of 20 or fewer kilotons should be considered non-strategic. If stricter criteria were desired, the limit could be set at 100 kilotons.
2) No launchers with an operational range (combat range in case of aircraft) of less than 2,000 kilometers should be capable of using or carrying any nuclear arms at all. Again, if greater strictness was desired the limit could be 5,000 kilometers - which is generally considered to be the limit of a theater, but the 2,000 definition is more likely to be acceptable, since many strategic targets are within theater range.
All stationary or land-mobile-but-not-launchable nuclear explosive devices, such as nuclear mines, nuclear demolition munitions, nuclear time-bombs, nuclear truck-bombs, nuclear suitcase bombs, nuclear container bombs and other non-launchable nuclear devices would either also be banned or at least limited in number (and still would have to exceed the 20kt or 100kt explosive power) by treaty and monitored. Some of these can be semi-strategic in nature, so it may be more difficult to ban them completely so at least do the next best thing and limit and monitor them if they prove impossible to ban.
The second problem would be verification. This would have to be done through 'national technical means', but would be considerably more difficult than the enforcement of strategic nuclear cuts. Nonetheless, it would probably prove sufficient method of verification.