The 2S7 Soviet "Peony" (Pion) or "Malka" is a Soviet self-propelled gun, designated 2S7 inRussia's GRAU index. Identified in the West for the first time in 1975 it was therefore classified M1975 by NATO (2S4 Tyulpan/Tulip also received the M1975 NATO code), whereas the official designation is SO-203 (2S7). The design is based on a T-80 chassis with the 2A44 203mm (8in) gun mounted towards the rear of the hull.

It carries four 203mm projectiles for immediate use with four more carried by a support vehicle. It is capable of firing nuclear ammunition of the same caliber. The gun has a range of 37,500 metres but the range can be extended to 55,500 metres by using Rocket Assisted Projectiles (RAPs). Pion remains the most powerful conventional self-propelled artillery piece since entering service in 1983.