Both Ukrainian and Russian forces have been relying on the older T-72 model tanks.
While not the most advantaged military kit, the T-72 are versatile, and unlike many Western tanks, equipped for tough terrain and the deep-fording of rivers.
The US has delivered hundreds of millions of dollars in aid, however, it has not offered any tanks to Ukraine because its military is using Soviet-era equipment.
The Biden administration has supplied Ukraine with at least 4,000 Javelin anti-tank missiles since the beginning of the invasion. Javelins can be fired so that the missile explodes on the top of a tank, where the armour is weakest.
Ukraine now has a 10-to-1 ratio of anti-armour missiles to Russian tanks.
President Joe Biden on Thursday announced a new $800 million commitment to Ukraine, including dozens of howitzers and tactical drones to fight Russia in the contested eastern Donbas region.
Mr Biden said the package was specifically designed to deal with the region’s flatter territory.
Russian president Vladimir Putin expected to overwhelm Ukraine with his military advantages, but nearly two months later, those advantages are vanishing, and the Ukrainians have put up a stiff resistance.