"Tactical nukes" already exist. It's just a matter of terminology. Strategic nukes are big bombs--lotsa blast power. Tactical nukes can be placed in shells and fired from cannons. They don't have so much blast power. The use of tactical nukes means that battlefield procedures have to change and fighting conditions have to change. The EMP from a nuclear blast plays hell with electronics. Tank crews will have to be shielded from

1) the explosion
2) the radiation

Tanks will have to be shielded from

1) the EMP
2) the heat

Soldiers in the blast area will be dead right now. So, the users soldiers will have to be shielded or not there. Read General Sir John Hackett's "World War III" or Tom Clancy's "Red Storm Rising." After the first shot, the world will never be the same. As Bee-dubya-ell so adroitly pointed out, it may not be possible to get the genie back in the bottle. And as Carol stated, "If they're talking about it they probably already have them." IMO, yep!