@The Deterrent very interesting. Your thoughts?
Very good observations, mostly correct. Tracking is not really an issue, I'm sure the S-400/500 can track ICBM class re-entry vehicles. However intercepting them is a different story.
Broadly speaking, Pakistan's missile program can be divided into three phases:
Phase-I:
The initial experimental phase in the 1980s, when Pakistan tried to establish a line of solid-fueled rockets, but was met with many failures ultimately abandoning these projects. The systems that were developed include:
1. Hatf-I TBM
2. Hatf-II TBM
Phase-II:
Established on existing systems from diverse backgrounds, with quite a bit of indigenous efforts.
1. Ghaznavi TBM (licensed DF-11)
2. Shaheen-I SRBM (improved DF-11A)
3. Ghauri MRBM (licensed Nodong)
4. Shaheen-II MRBM (based on technologies from Shaheen-I, with Chinese inputs)
5. Babur-I GLCM (reverse-engineered Tomahawk)
6. Raad-I ALCM (based on Babur-I)
Phase-III:
Upgraded systems from Phase-II, utilizing local R&D. These will form the front-line of Pakistan's nuclear delivery options in the future. Key thing to note is that Pakistan is streamlining its systems with respect to warheads, avionics and propulsion.
1. Nasr TBM
2. Shaheen-IA SRBM (improved Shaheen-I [better fuel, advanced avionics, miniaturized warhead])
3. Shaheen-III MRBM (improved Shaheen-II [better fuel, advanced avionics, miniaturized warhead])
4. Babur-II GLCM (improved Babur-I [more fuel, advanced avionics])
5. Babur-III SLCM (submarine launched variant of Babur-II)
6. Raad-II ALCM (in development)
7. MIRVed System (in development)