The T-72 series tank was developed as a direct prototype of the T-64 mechanical issues correction. In 1962, while working on the corrections of production problems, specially engine and firepower, a new prototype was developed with the 2A46M 125mm smoothbore gun and the V-45K diesel engine. This prototype was renamed to Object 172. While being in an unclear political process, decree number 326-113 was issued, freeing Uralvagonzavod from the production of the T-64A. The first batch was produced and set under the name of "Object 172M". It was tested again in 1972 and accepted to service under the name of T-72. License production was sold to multiple countries as well as unit batches to Warsaw pact nations and exported to other countries such as India, Syria, Finland, Iraq and Yugoslavia. After the collapse of the USSR in 1991, some of the independent countries kept the tanks such as Ukraine.
-From WT Dovbleg