The MGR-1 Honest John rocket was the first nuclear-capable surface-to-surface rocket in the US arsenal. Designated Artillery Rocket XM31, the first such missile was tested in 1951 and deployed in January 1953. The designator was changed to M31 in September, 1953 and were deployed in Europe several months later. It is important to note that alternatively, the missile was designed to be capable of carrying ordinary high-explosive warheads, even though that was not the primary purpose for which it was envisioned.
The M31 consisted of a truck-mounted, unguided, solid-fueled rocket transported in 3 separate parts. Before launch they were combined in the field, mounted on an M289 launcher and aimed and fired in about 5 minutes. The rocket was originally outfitted with a W7 dial-a-yield nuclear warhead with a yield of up to 20 kilotons and later a W31 warhead with a yield of up to 40 kt. It had a range between 5.5 km (3.4 miles) and 24.8 km (15.4 miles).
In the 1960s Sarin nerve gas cluster munitions were also available for Honest John launch.
There were 2 versions:
* MGR-1A had a range of 48 kilometers, takeoff thrust of 400 kN, takeoff weight of 2720 kg, diameter of 580 mm and length of 8.32 m.
* MGR-1B had a range of 37 kilometers, launch thrust of 382 kN, launch weight of 2040 kg, diameter of 760 mm and length of 7.56 m.
Production of the MGR-1 variants finished in 1965 with a total production run of more than 7,000 rockets. The system was replaced with the MGM-52 Lance missile in 1973, but was deployed with NATO units in Europe and US Army National Guard units as late as 1982.