The fear is that since the bomb is so small ( any strong man can lift 40 - 50 kg. dumbbell , here it is nuke bomb ) any jihadist inspired army man ( there are lot of jihadist elements in pak. army , hence we see support for terrorist in pak. army ) may randomly fire many weapons on Indian army than actually required , ( Not even one should actually be fired to avoid nuclear Armageddon ) , say there is Kargil War and pak. army fires from other side of mountain on Indian positions , India will then have to respond , and the response will be atleast one 12 Kt. Nuke bomb ( I am estimating Indias smmallest Nuke from 1998 Shakti 2 nuke test ) , and it will destroy quite lot of things than intended and Pak. will again response. So you see how close tactical weapons can bring nuclear exchange it is this thing that U.S.A. is worried about.
Correcting a few assumptions which are 100% wrongly placed here. If you are on a brain washing or Propaganda mission, please find some other place to lay your ideas.
There are two main reasons which makes me think that your claims are quite erratic and you are talking nonsense.
1. Your example of kargil is ridiculous and reading it is a waste of time. Cold start by India is poised with major armoured forces in the south of Pakistan, not mountains. Basically you have no idea about cold start and the utilization of nasr.
2. Your example of Jihadi inspired army man and weapons falling in wrong hands means you have no idea about command, control and promotion methods of PA. You have not done your homework boy.
There are no "jihadi inspired army man" in PA. If there were, things would have gone wrong in the PA by now. This is not a GI JOE movie, this is real life. Stop watching hollywood crap. However, if this fear makes you lose your sleep at night, consult a good psychiatrist.
PA is not a rogue army, its a professional army. There is a proper command and control structure for nuclear weapons and other missiles. You can forget random missiles being fired at the Indian army unless you know about the structure and how the officers are chosen to lead such formations. Putting weapons in hands of a group of soldiers, laughable statement.
If you dont know, then ask, but stop talking rubbish.