IM wanted to nuke Surat, Yasin Bhatkal tells cops | idrw.org
I don't believe that it would be wise to simply dismiss this as unlikely without some analysis.
It can be assumed that Pakistan does have warheads that weigh about 500 kg or so and such a warhead would first have to be handed to terrorists by the Paki army (or stolen) and carried in a truck to Surat or wherever. The large size and weight make this possibility a little daunting for a terrorist. Many things are smuggled - but a 500 kg warhead suffers from the twin problem of being released/stolen in Pakistan and even if it is escorted to the border by Hafiz "oinkoink" Saeed there remains the problem of smuggling a large bomb into India.
More likely it would have to be a "small" bomb as mentioned by Yasin.
I had previously done some (open source) research into small bombs and had made notes. I located them and let me post some known facts.
Regarding the feasibility of Pakistan having such a bomb to be given away to terrorists, there are a few technical points
Even after that the yield is very low - just 20 tons (not kilotons) - which is the bomb load of 4 F-16s. 15-20 kg of Plutonium can be used to make 4 to 8 proper nuclear bombs of dozens of Kilotons and are wasted in a small bomb. Nevertheless, it is technically feasible although I suspect Pakistan cannot spare that much Plutonium for a single low yield bomb to be carried by a terrorist group.
I wonder if Pakis really do have a warhead that fits into a Hatf size missile (30 cm diameter) which can be smuggled by terrorists. As mentioned above this take a lot of Pu and gives a very low yield. In fact i suspect Pakistan may not have enough Pu to spare for Hatf missiles because they are so wasteful of Plutonium.
I have read that Pakistan was producing Plutonium at 10 kg per year in 2007. That means that by 2007 Pakistan could either produce two "proper" warheard of 5 kg Pu each, or wait 2 years to produce one low yield, small/miniature werhead with 15 kg Plutonium. Of course Pakistan may now be producing 30 kg Pu per year - and may have manufactured a few 'wasteful" small warheads.
The question is whether these small warheads can be smuggled out of storage and then smuggled into India. In would seem to me that the TTP would be as keen as the LeT to get a warhead. Only the TTP may find it easier to smuggle the warhead into areas in Pakistan or Afghanistan and use it there.
There has gradually been a merging of training and resource assets of Taliban and LeT - as reported in various media. And although the LeT is pro Paki army and the Taliban are partly anti-Paki army, it will not be certain where a stolen warhead will go. The Paki army could give a warhead to the LeT for "deiability" but it is difficult to claim that a nuclear bomb came from a madrassa in FATA. The best way of hitting Surat, or for that matter Delhi would be via missile rather than terrorist bomb. If a bomb that was being smuggled across the border is caught the Pakistan will not be able to live that down.
Just my thoughts..