The 2S9 Anona ('Anemone') is a self-propelled gun/mortar designed to be used by Soviet and Russian airborne units (VDV) in order to fulfill the role of an indirect fire gun platform but also to offer anti-tank support. The 2S9 features an aluminum hull based on the BTR-D airborne APC (a variant of the BMD-1 IFV), with a driver and commander compartment located in the front of the vehicle and a crew compartment behind it. The engine compartment is located in the rear. The 2S9 is armed with a 120-mm 2A51 gun/mortar. It can fire conventional mortar bombs to a distance of nearly 9 km, extended to 13 km using rocket-assisted projectiles. Unlike most gun and mortar platforms, however, the 2S9 also has a direct fire role where its principal armament is a HEAT projectile capable of penetrating up to 650 mm of steel armor. The 2S9 is also capable of coming in and out of action in just 30 seconds, and can raise its suspension to provide additional firing stability. It is also fully amphibious, being propelled by two water jets in the rear. Defensive armament is not equipped, however, although there is NBC protection. Given its small size, the 2S9 is air transportable by most Soviet medium and heavy transports and can be paradropped by the An-22, An-32, and Il-76. The 2S9 first saw action in Afghanistan, and later in the wars in Georgia, Syria, and more recently in Ukraine (by both sides) and it is also used by the ground forces and naval infantry as well. Export clients include numerous former Soviet states as well as China, Syria, and Venezuela.

The 2S9 Anona was designed in the second half of the 1970s and was identified by NATO in 1985, thus receiving the M1985 designation. It has also been known as the SO-120. A modernized version is known as the 2S9-1N Nona-S (the change in name being an abbreviation of 'Newest Ordnance of Ground Artillery'), while a version using the BTR-80 as a chassis is known as the 2S23 Nona-SVK.