File photo: Hwasong-10 (Musudan) IRBMs seen at a military parade in Pyongyang
U.S. officials at the Pentagon are linking the Khorramshahr MRBM to that of the Hwasong-10 (aka BM-25, Musudan) mobile intermediate-range ballistic missile developed by North Korea.
According to Kyle Mizokami:
An anonymous U.S. government official told Reuters the missile was launched from a test site near Senman [sic], east of the Iranian capital of Tehran, and said it was the same type of missile last tested in April 2016.
As pointed out by arms control expert Jeffrey Lewis on Twitter, the Pentagon identified the July 2016 missile as a locally produced version of the Musudan, a North Korean intermediate-range missile. Also known as the Hwaso
The Musudan has been adapted from a submarine-launched missile to a road-mobile missile, and is launched from 12-wheeled heavy transporters. The missile has a payload of 2,000 to 2,500 pounds and a theoretical maximum range of 2,500 miles. The range of the missile is open to some debate because so far, despite Pyongyang's claims to the contrary, it hasn't been successfully tested. North Korea may have launched as many as eight Musudans in 2016 alone, and not a single launch was considered successful by outside observers.COMMENT: Iran has yet to publicly unveil an adapted design related to the Hwasong-10. However the Khorramshahr has been verbally publicized on 25SEP2016 by MODAFL Brig. Gen. Hossein Deghan at an assemblage of Iran’s Parliament.
U.S. intelligence sources are said to have ascertained this ballistic missile type. If accurate, then the Khorramshahr ballistic missile project is likely being developed and tested by Iran’s Aerospace Industries Organization (AIO).
It is possible the Hwasong-10 and Khorramshahr projects may represent a binational, dual agency approach towards the development, testing and production of an IRBM.
Note: another possible explanation for the test is that it's related to Iran's Simorgh ("Phoenix") series space launch vehicle (SLV) program.
Currently the UNSC has referred the 29JAN2017 Iranian test launch to its committee on Iran, for investigation.