An 81 mm mortar is a medium-weight mortar. It is a smooth-bore, muzzle-loading, high-angle-of-fire weapon used for long-range indirect fire support to light infantry, air assault, and airborne units across the entire front of a battalion zone of influence. Many countries use or used an 81 mm mortar in their armed forces. Examples are: Warsaw Pact countries and China use a similar 82 mm caliber for the same purpose.