Short answers, pulled from the story.
The T-80 entered Soviet service in August 1976, becoming the first production tank in the world to be powered solely by a gas turbine engine. It was designed by Soviet engineer Nikolay Popov and manufactured at the Leningrad Kirov Plant.
The T-80's gas turbine engine consumed nearly as much fuel at idle as under full power, and many crews exhausted their fuel reserves while waiting before the assault on Grozny began in December 1994. The tanks were also used in urban combat for which they were not suited, some lacked explosive reactive armour inserts, and rocket-propelled grenade teams attacked from cellars and rooftops targeting the least-armoured sections. Russia lost 18 of the 84 T-80 tanks used by the 133rd and 3rd Tank Battalions over three months of fighting.
South Korea acquired 35 T-80Us through Project Brown Bear, a program that collected Russia's unpaid debt from a $1.47 billion loan made in 1991, with weapons purchased at a 50% discount. South Korea received six T-80Us in 1996-27 more in 1997, and two additional T-80Us in 2005.
The original T-80 is powered by a gas turbine engine, while the T-80UD uses a 1,000 hp 6TD six-cylinder diesel engine developed by the Morozov Bureau in Ukraine. The diesel variant offers better fuel efficiency and longer range; roughly 500 T-80UD tanks were built at the Malyshev plant between 1987 and 1991.
The T-84 is based on the T-80UD. Its development accelerated after Russia blocked Ukraine's T-80UD exports to Pakistan in 1997 by withholding critical components including the 2A46-2 125 mm guns and cast turrets, forcing Ukraine to develop domestic alternatives such as a welded turret. The T-84 Oplot, first delivered in 2001, incorporated turret-bustle ammunition storage.
According to the open source intelligence website Oryx, as of February 2026, at least 1,274 Russian T-80s of multiple variants have been visually confirmed as destroyed, damaged, abandoned, or captured. The largest single category is the T-80BV, with 708 confirmed losses.