The 2S31 Vena (Russian: "2С31 Вена") is a Russian amphibious self-propelled 120 mm mortar system. "2S31" is its GRAU designation.

The 2S31 consists of a 120mm 2A80 rifled gun-mortar mounted on the chassis of the BMP-3 infantry combat vehicle.^[1] It was developed by Joint Stock Venture "Plants of Motovilikha" (Russian: ОАО "Мотовилихинские заводы"). The 2S31's turret is equipped with digital automated fire control system, navigation system, and optical/electronic reconnaissance and target acquisition system. Its 2A80 gun-mortar is capable of launching a high-explosive mortar projectile with a maximum range of 18,000 m (20,000 yd).^[1] The vehicle is protected by a welded aluminium hull to protect against small arms fire and shrapnel.^[2] It can also fire armour-piercing projectiles that can penetrate up to 650 mm (26 in) of steel plate at ranges of up to 1 km (0.62 mi). A separate sighting system is used when engaging in direct fire mode.^[3]

Reportedly first combat use of Vena was during Second Nagorno-Karabakh War.^[4]

In September 2023 Vena appeared in Vesti program during the report about Russian troops fighting near Bakhmut, confirming its use during Russian invasion of Ukraine.^[5]

•  Azerbaijan^[1]
•  Venezuela^{[1][unreliable source?]}
•  Russia^[6]

• 2S9 Nona