Nothing to disagree with . It just happens that Islamabad is likely to try a launch-all-at-once ( meaning whatever is available at that time ) to cause unacceptable damage and see if the adversary can be rendered incapable of launching nukes . The targets are most likely to be major cities , industrial hubs , militarily significant areas and resources . Even if the rivers are contaminated , the whole of our populations and economy is done-with . I do not really see the survival and continued existence after a exchange , it wasn't present with the math you did here even , if the data is extrapolated even to 50% of both country's arsenal .
That's the thing, every country in the world would like to launch all their arsenal at once to give maximum punch and attain maximum surprise, but in times war it doesn't happen, that is why multiple redundancies are prepared.
When your enemy see's you assembling and mating hundreds of nukes with their missiles, won't it figure out that you are readying to launch an all out nuclear strike and launch preemptive strike on your nuclear assets. Especially if that enemy has SSBNs deployed of your coast, ready to strike at moments notice.
If Pakistan is at a disadvantage because of inability to deploy the whole arsenal in emergency so is India . I agree with the limited land mass theory and the problems it presents , though the world's 36'th largest country still has enough areas to disperse and look for second strike when the opportunity presents itself . Of course this is all hypothetical .
Well the fact is Indian land mass is almost 4 times bigger than Pakistan's , hence shielding them/ deploying them is so much easier.
On top of it, India is planning to deploy a major chunk of it nukes on submarines, where they are already canisterised , assembled, ready to fire at a moment's notice.
India has 1 SSBN in sea trials, 3 SSBNs under construction each housing 12 nukes. She has already inducted one SSN and is negotiations for the second with the ability to convert it into a SSGN, if the situation demands.
Both our countries have primitive nuclear weapons with sub-kiloton yields - these aren't effective TN warheads yield <50 kT , what other nuclear powers except North Korea have their biggest yields in kT even ? This is what the others have achieved with fission only warheads . Pakistan claims a yield of 18kT with its thermonuclear test , India does 45kT - both the claims are disputed by the independent sources and believed to be much less than claimed . It is highly unlikely that either of the side can perform an effective decapitation strike and prevent the adversary to launch nuclear weapons . There's a reason why I said that both countries are almost matched non conventionally . There's a reason why this article calls MAD as not an option for India .
Pakistan never tested or even claims to have tested a thermonuclear device, maximum it is tested was boosted fission device.
India's Shakti 1 test was a thermonuclear device 45 Kt yield.Basically exactly same design of weapon(which was tested in Shakti 1 can give a yield of up-to 200 Kt.. the yield of the weapon was intentionally kept under 50 Kt to avoid damaging the nearby villages .
The fact is a thermonuclear reaction, once achieved in a Teller Ulam can be stepped up to achieve what ever yields.
A country's ability carry out a decapitation strike on an adversary is dependent it ability to gather intel on enemy nukes and launch vehicle and on the adversaries ability to disperse and hide its nuclear weapons.
The above task becomes almost impossible if the enemy arsenal is hiding under the seas.
Land based assets much more vulnerable to enemy's decapitating, conventional and nuclear strike.. Fixed Silos are very vulnerable to pin point nuclear strikes.
The Shaheen IA is widely believed to be testbed for upcoming technologies , the increased ranges and speed weren't of much importance , as was the Post Separation Altitude system - automated refueling and limited stealth features . Maybe , not ground breaking but still the first step in developing and testing counter-measures . Almost all antimissile system - even those deployed by the U.S aren't believed to intercept more than 50% of incoming hostiles .
Post separation altitude correction system is there in all the Shaheen missiles, it is basically there to give better accuracy.
Claims that PSAC can help evade anti missile are pure hokum. As PSAC helps the warhead(after separation) keep its trajectory..when it starts deviating off course( to achieve better accuracy)...thereby making its path more linear and easier to intercept.
Automated refueling has again no bearing its anti missile evading ability.
This 50% figure might be true for single anti missile battery trying to intercept a host of incoming missiles. Thats is why most of the countries use multi layered missile defence
eg US has three layers of missile defence.
Strategic missile defense- NMD(to intercept missiles in boost or mid course) followed by Theater missile defense THAAD(to intercept them in terminal phase further followed by Tactical missile defense(Patriot).
India is initially planning to deploy dual layered anti missile sys ,
with a interception probability of 99.9% against missile of 2500 Km range. Upper layer will be PDV(similar to THAAD) and lower layer will be AAD( similar to Patriot)
Another layer consisting of AD-1 and AD-2 (having higher range/speed for midcourse interception against ICBMs will be added at a later stage.