It is not as big a challenge as we make it out to be IMHO.
Countries like Iraq (before the war) and Thailand (more recently) have developed tactical SRBM's that in most cases did not exceed the UN mandated 150km range limit. The technical development level of these countries aren't overly sophisticated compared to ours. However they had unmitigated military and political will. They also lacked sycophants and ingrained embedded foreign 'dalals' like we currently have.
Iraq's example was the Al-Samoud (and solid fuel variant Ababil 100). Thailand's solid fuel tactical SRBM is known as simply DTI-1 and is launched from a launcher which is a variant of their larger unguided 300mm MLRS launcher they field. These are (other than larger diameter of ~500mm) similar to the A-100 fielded by Pakistan and Weishi variants from China with add'l guidance and dynamic thrust variance sophistication. Tactical SRBM's with conventional HE warheads are great in terms of area denial and simple defence 'bang-for-the-buck'. As long as you keep range under 150 KM you're doing great.
Last but not least - even Houthis in Yemen are using modified SA-2's (Qaher) against Saudi targets. No one is condoning terrorism or counter-terrorism here, all that is being said is that the technology is well-proven (and has been since the 70's). Fabricating these things is not overly difficult.
Here is the write-up for the Al-Samoud from Globalsecurity,
"
Al-Samud
Iraq worked on the two SRBM systems with ranges of less than 150 km authorized by the United Nations: the liquid-propellant Al-Samoud, and the solid-propellant Ababil-100. The Al-Samoud is essentially a scaled-down Scud, and the program allowed Baghdad to develop technological improvements that could be applied to a longer range missile program. According to the CIA, the Al-Samoud missile, as designed, was capable of exceeding the UN-permitted 150-km-range restriction with a potential operational range of about 180 kilometers.
The Al Samud I was designed to carry a unitary HE warhead, and Iraq apparently intended to develop a conventional submunition warhead for the missile. The Al Samud HE warhead is an extrapolation of the Scud warhead design and was later adopted for the Al Fat'h missile. Development of the warhead took about eight months and was completed in the summer of 1994. The Al Samud warhead components are listed in Table 2. The original Al Samud warhead has a 500-mm-base-diameter and is 2 meters long with a design payload mass of 300 kg.
The fuze mechanism is similar to that of the Scud missile. The original warhead design contained one forward booster and two rear boosters at the base of the warhead, one of which serves to provide uniform detonation in the system, the other as an auto destruct mechanism in case the missile deviates from its predetermined trajectory. Because Iraq lacked confidence in the accuracy of the guidance and control system, the backup and emergency boosters were never incorporated, leaving a single forward booster. An impact crush switch is incorporated into the graphite nose of the warhead.
Iraq's desire to achieve 150-km range resulted in a quick modification to reduce the payload mass from 300 kg to 200-250 kg with 100-120 kg of HE, according to a senior missile official. Iraq reduced the warhead mass by relocating the base plate and bulkhead forward into the warhead body, which reduced the available HE volume. Warhead modifications continued into 2001. A flight test in late 2001 used better constructed cylindrical and conical parts of the warhead with a payload of 240 kg and achieved a range of 151 km.
Al Samud Warhead Components
Nose Tip: Graphite
Outer shell: 2-mm rolled steel
Insulation layer: 3-mm Asbestos
Inner Shell: 1-mm rolled steel
Fuze Impact or crush switch: housed in nose tip
Booster x 3 (The third booster acts as a safety mechanism, detonating if the missile deviates from its predetermined trajectory)
Filler 60% RDX, 30% TNT, 10% aluminum powder
After the Commission's monitoring system in the missile area became operational in August 1994, Iraq's non-proscribed activities in the missile area moved closer to a production phase. [
S/1997/301] Iraq resumed its acquisition efforts in support of its missile facilities. Iraq placed a number of orders, both directly and indirectly (through middlemen and front companies), for the purchase of equipment, technologies, supplies and material for both missile- and non-missile-related activities at these facilities. Iraq explained that many of these efforts were in direct support of its Ababil-100 program for indigenous development and production of surface-to-surface missiles with ranges between 100 and 150 kilometers. [
S/1995/864]
After August 1995 Iraq admitted that since the adoption of resolution 687 (1991), it had carried out an undeclared program to modify the Volga/SA-2 surface-to-air missile system to a surface-to-surface application with a range of over 100 kilometers. At the initiation of the monitoring system in 1993, the Commission decided that it would be sufficient to monitor, including with cameras, sites where main maintenance activities were carried out on Volga systems. As Iraq's undisclosed program comprised flight tests of this system, the Commission decided, in January 1996, to modify monitoring modalities to include tagging of all Volga missiles similar to other tagged missiles in Iraq. [
S/1996/848]
Iraq had continued its development of the Al-Samoud missile system, which had a declared range of less than 150 kilometers. The term "al-Samoud" is not attested outside of UNSCOM and derivative documents. The phrase "Al-Sumood" may be translated as "steadfastness" or "endurance" -- conveying a sense of national endurance of suffering. The Sumood of the Palestinians gave way to the Intifada in 1987. Among the meanings understood from the root "samada" is the raising of ones head up proudly or in disdain. [The rather unlikely kindred homonym "Samood" occurs frequently in the Koran, also transliterated "Thamud", to refer to a tribe that rejected the teachings of the Prophet, with meanings that include The Mud, The Mire, The Bog etc...]
The issue of reuse by Iraq of Volga surface-to-air missile components in the development of the Al-Samoud missile remained unresolved.[
S/1998/920] UNSCOM expressed serious concern over the use by Iraq of certain key components taken from the Volga surface-to-air missile system and modifying them for use in a short-range missile system. These modifications could, in turn, have enabled Iraq to modify the Volga missiles into a proscribed surface-to-surface mode. [
S/1998/529] The covert G-l program, to convert surface-to-surface missiles to a proscribed surface-to-surface role, included secret flight tests and an undeclared facility to support this (1993-1994).[
UNSCOM 03 June 98]
from AEQUS in India (steel-forging facility like this can be quite easily duplicated in Bangladesh given there is demand for the output of the facility from defense). Maybe a Pakistan Army expert (
