The Shahab-6 is expected to have a range of 5,470-5,500 and 5,632-6,200 kilometers with a 1,000-750-500 kilogram warhead. This range capability will depend on the number of stages used in the launch vehicle and their performance. December 1996 news reports claimed that Iran is developing a 3,500-mile (5,632 kilometers) range missile called Shahab-6 that would be capable of reaching Europe. The technology for this system was cited as coming from Russia and North Korea. Reportedly the missile would become operational by the year 2,000, though others reports claim that Iran intends to complete the development of this system within five to ten years. Presumably this missile will turn out to be a totally redesigned Taep'o-dong-2/NKSL-X-2 Iranian first stage derivation with new redesigned shorter larger diameter second and third stages.
Quoting from the Oct. 1, 1998, The Washington Times, "Israeli, Prime Minister Mr. Benjamin Netanyahu said, "Iran is developing the Shahab-4 which can reach well into Europe, and the Shahab-5 and 6, which (will have the capacity) to reach the Eastern Sea board (of the United States)". The article went on to quote from the Blue-ribbon Congressional Commission --- headed by then former Defense Secretary Donald Rumsfeld.
"In addition to this Scud-based long-range ballistic missile program, Iran has acquired and is seeking major, advanced missile components that can be combined to produce ballistic missiles with sufficient range to strike the United States, "----." (1)
The following information was provided from the July 16, 1999, The Washington Times article. Iran's Kosar launch vehicle was suggested to be the Iranian variant of the North Korea's Taep'o-dong-2 booster. The new missile was said to be undergoing design development with assistance from Russian aerospace technicians and state-run entities. It was suggested that it could be powered with a version of Russia's storable liquid propellant RD-216 closed cycle two engine cluster in its booster first stage. The RD-216 is an Energomash engine originally used on the Skean/SS-5/R-14, IRBM, Saddler/SS-7/R-16, ICBM and Sasin/R-26 ICBM missiles developed during the cold war. It is still used on the C-1, Kosmos/SL-8 Russian space booster. This does suggest fairly strongly that Iran has acquired through elicit means the designs of both the SS-4, RD-214 and the SS-5, RD-216 storable liquid propellant rocket engines and the SS-4 missile body production technology. This is questionable but gives some insight into the Taep'o-dong-2 first stage design. It was based on new information suggesting there had been another rocket engine technology transfer from a Russian rocket engine entity Energomash. (2) No further clarifying information on this has since surfaced.
This unproven rocket engine technology transfer from Russia to Iran would not give Iran the engine documentation or the actual hardware. Nor did it give the Iranians precise engineering drawings of each part or the materials and technology to produce and duplicate that technology. The only application where the Iranians could apply this acquired rocket engine technology is in the Shahab-5 and Shahab-6 boosters programs. However this assumes the Iranians can even produce the engines. Certainly that will take them years beyond their intended design development cycle for those launch vehicles in order for them to assimilate that rocket engine technology. Therefore they are left with no other alternative but to work with the North Korean engine technology in their possession and their rework of it for the Shahab-5 and Shahab-6 programs in cooperation with North Korea.
Ultimately Iran will have to redesign the upper stages of the Taep'o-dong-2, Shahab-5 booster in order to improve its performance to meet the Shahab-6 requirements. This is because of its design aspect ratio, the length to diameter of each stage and the total vehicle length to diameter design and its upper stage mass fraction, the upper stages total structural mass as a function of the aspect ratio that should be minimized. It will also have to develop more powerful storable liquid propellant rocket engines beyond those they are now working with for Shahab-5. This will take Tehran five to seven years under the most optimum of conditions assuming it has the political will, economic vitality, facilities infrastructure, materials, in addition to the trained, educated and experienced personnel to support such an expensive effort of this magnitude. At this point it is far from being a credible threat to the United States.
Presently the Shahab-6 is a design study concept with a better mass fraction and aspect ratio than that of the Shahab-5. That is its upper stages will be shorter and larger in diameter similar to the Chinese CSS-3, and CSS-3A LRICBM. The second stage will probably be the same diameter as the first stage but only time will clarify this design issue. This is where Iran will finally start developing large missiles from scratch on its own beyond what it is doing with Shahab-5. It will take some years for this design of the Shahab-6 to manifest itself as the Shahab-5 the Iranian variant of the North Korean Taep'o-dong-2 nears completion. Several design variations are possible. The concept drawing on this web site only displays the total growth potential implication as displayed in the new North Korean Taep'o-dong-2 gantry umbilical tower. That design is a non-flyable design. The bending moments would break the missile up very early in flight. Thus the Shahab-6 has to be shorter and have larger diameter upper stages than those used in the Taep'o-dong-2 upper stages in order to be flyable.
On February 9, 2000, The Washington Times, disclosed the following information, "The  engines arrived in Iran on Nov. 21, (1999) after they were spotted being loaded aboard an Iran Air Boeing 747 cargo jet that left Suinan International Airfield about 12 miles north of-----Pyongyang (North Korea)". These are the same engines used in No-dong MRBM.
The article went on to state that China is continuing to "sell missile technology to North Korea despite promises ---", and that the North Koreans continue to prepare to flight test the Taep'o-dong-2 launch vehicle.
The article went on to describe several design alternatives for the use of the engines by Iran that could be used to create a Taep'o-dong-2 class booster. When considering the Shahab-5, 6 class booster they could utilize a new first stage equipped with multiple No-dong engines and a second stage equipped with one or more No-Dong engines with a solid motor third stage and warhead. The final concept presented suggested a new first stage equipped with a Russian engine or engine cluster topped with a single or multiple No-Dong engines for a second stage with a solid motor third stage with a warhead. Some of these alternative concepts would certainly address the Taep'o-dong-2 mass fraction and stage aspect ratio problems but such improvements may have to wait for the introduction of the Shahab-6 launch vehicle. (3)