4000KM!!....Ahhhh I dont think so,not unless you`re planning on having zero payload on the damn thing[LOL!].The dprk was struggling to even get 3500km out of it with a 500-1000kg nuclear warhead.I also remember iran stating that this would be used to carry heavyweight payloads out to medium range,not lightweight payloads out to intermediate.
Frankly at this point theres little further pressure that the west can bring to bare and its not like they need any excuse to engage in economic blackmail and thuggery regardless of whatever iran does anyway.Irans ballistic missiles are neither a part of the jcpoa nor prohibited under any un resolution,plus they seem to be one of the few things outside of the nuclear program that supposedly worries the west,I think its past time that iran reminded them why this is.
Ultimately sitting back and doing nothing while hoping that chump will go away and the eurovassals will grow some balls is just not a viable strategy......and never was.
And lastly on a more practical note,larger payload capable missiles like this will likely be the future of irans deterrent force as they can not only carry more than one guided warhead they can also carry decoys and countermeasures against the existing and future abm systems in the region.After all what makes better sense from a perspective of military effectiveness,one warhead per missile from the existing force or multiple warheads plus penetration aids and decoys from a slightly larger missile?