The Ukrainian army entered the war with some 800 active T-64 tanks. In the 11 and a half months since Russia expanded its attack on Ukraine, the Ukrainians have lost about half of their 40-ton T-64s.

Yet unlike the T-72 and T-80, there are not many external sources for more T-64s, unlike the other large tank types in Ukraine, the T-72 and T-80. Every T-64 the Ukrainian military loses is likely one it cannot replace.

This explains why Kyiv has been lobbying its partners for main battle tanks similar to those used by NATO. Once T-64s are depleted, the Ukrainian army must move to new, more durable tank variants.

The T-64 is unique among Soviet-style tanks. In the early 1960s, the Soviet Army used mainly the T-54/55 and the more recent T-62. The first has a 100-millimeter main gun; the second a 115-millimeter. Both types have a crew of four, including a loader.

Aiming to take a generational leap in mobility and firepower, the Morozov Machine-Building Design Bureau of Kharkiv in northeastern Ukraine had been working on the T-64. The new tank replaced the smaller diameter one, the T-64, and became the first T-64 in history. The new tank replaced the smaller diameter guns of the T-54/55/62 line with a new 125-millimeter gun.

The T-64 also included a fast but mechanically complex autoloader in place of the magazine, reducing the crew to three. The earlier vehicle types’ cumbersome but weaker powertrains have been replaced with a new 700-horsepower diesel engine and compact transmission. Using the savings from the additional subsystems, the designers increased the thickness of the armor.

The result was a fast, heavily armed, and thickly armored tank that, on paper, at least matched contemporary Western tanks. But the T-64 was complex, difficult to build, and expensive. 

So, while the best Soviet forces were re-equipping with the Ukrainian-made T-64, the Soviet Army began developing a cheaper alternative. The resulting T-72 had a simpler but slower autoloader and a less complex transmission. Also, the T-72 is manufactured in Russia at the Uralvagonzavod factory in Nizhny Tagil.

Since the introduction of the T-64 in 1963, the Soviet Union has had two parallel tank lines. The T-64 evolved into the T-80. Meanwhile, the T-72 evolved into the T-90. But the T-64 had Ukrainian DNA and was made in Ukraine by some of the best engineers and skilled workers in the Soviet Union.

Although the factory for the T-80 was in Russia, after the dissolution of the Soviet Union, the Russian military gradually standardized on the simpler and cheaper T-72 and T-90. The Ukrainian military, for its part, stuck with the T-64 and, to a lesser extent, a turbine-powered version of the T-80.

After five decades, the T-64s were on the verge of obsolescence. Her guns, engines, and autoloaders were still working well, but her optics—including a passive infrared sight that required a matching infrared spotlight—was outdated, and her armor poor.

The Russian invasion of the Ukrainian Crimean peninsula in 2014 prompted the Ukrainian Ministry of Defense to renew the T-64 fleet. The new T-64BV variant features modern optics, including a passive infrared sight -no projector-plus tight reactive armor blocks.

The T-64BV is capable of defeating even the most advanced Russian tanks.In the pitched clashes that took place outside Chernihiv in the first weeks of the current war, the Ukrainian Army’s 1st Tank Brigade deployed its approximately 100 T-64BVs in the woods between Chernihiv and nearby Kyiv.

As the Russian tanks passed, the T-64BV crews would open fire at point-blank range, counting on their faster autoloaders, giving them an advantage over the Russian crews. In the end, the 1st Tank Brigade won the Battle of Chernihiv.

But Russia’s broader war against Ukraine gobbles up tanks at a staggering rate. Somewhere around 1,500 Russian tanks have been destroyed. The number of Ukrainians is estimated to be around 400. That’s about half the number of tanks each side had planned to use in this conflict.

The Russian military has large reserves of old but salvageable tanks, including thousands of T-62, T-72, T-80, and T-90. The Ukrainian army has lost at least 500 tanks. 

The reserves of the Ukrainian army are shallower. The Kharkiv and Kyiv tank farms could house 450 war reserve T-64s, according to a recent count by an open-source intelligence analyst.

No one knows how many are good candidates for reactivation. Three to four decades of open storage can be hard on a tank.

All the other usable T-64s in the world belong to Uzbekistan, Transnistria, the Democratic Republic of the Congo… or Russia. It is safe to assume that Kyiv is not going to get any T-64s from abroad.

Since the Russian and allied forces have not stationed many T-64s in Ukraine, the Ukrainians have not had many chances to seize unharmed ones. Although the Ukrainian army has captured more than 500 Russian and separatist tanks, only seven are T-64s.

At some point, possibly within a year, Ukraine will run out of T-64s. Although the Kharkiv tank plant could make some new examples using long-stocked components, it is unlikely that the plant will be able to keep up with losses that, so far, have averaged one T-64 every day, plus or less.

The Ukrainian army must make a big tank transition. It is unavoidable. Although large shipments of Polish-made PT-91s (highly improved T-72s) could delay the inevitable, the day is fast approaching when the Ukrainians must re-equip their brigades with European and American tank types Leopard 1 and 2 German, British Challenger 2 American M-1s.

The magnitude of Ukraine’s main battle tank needs – some 1,500 tanks in active service plus a few hundred in maintenance or training bases – puts into context the roughly 300 Leopard, Challenger 2, and M-1 that Kyiv’s allies have promised so far. Now. Three hundred tanks are too few. Within a year, Ukraine might need another thousand.