The West has answered Ukrainian President Volodymyr Zelenskyy's calls for tanks to be delivered to Kyiv to defend his country against the Russian invasion.
President Joe Biden announced on Wednesday that the US would send 31 M1 Abrams tanks in a reversal of policy, as Washington had previously suggested its tanks were not the correct tool for the conflict because they are difficult to operate and need a lot of fuel.
German Chancellor Olaf Scholz also announced that Berlin would send 14 Leopard 2A6 tanks to Ukraine, paving the way for other European nations to do the same with their German-made tanks. Mr Scholz had been facing pressure from western allies after he initially refused to send the Leopards out of fear that doing so would escalate the war.
The UK has already announced it would deliver 14 Challenger 2 tanks to aid Ukraine's counter-offensive.
Mr Zelenskyy had pleaded with western allies to send tanks as the war against Russia rages on, and now it appears he will receive the requested materiel to bolster Ukraine's counter-offensive efforts.
The Leopard 2 is a German-made battle tank that is used by armies throughout Europe and in Canada.
The tank is armed with a 120mm smoothbore cannon and has a range of up to 450km. The Leopard 2 is also armed with two machine guns.
The Leopard 2 is manned by a four-person crew: a commander, a gunner, a loader and a driver.
It can travel up to 70kph, allowing it to move speedily even on rough terrain, and it is powered by a 1,500 horsepower engine using diesel fuel.
Berlin must give its consent for other nations to export the German-made vehicles to Ukraine. There are about 2,000 Leopard tanks across Europe, CNN reported.
The M1 Abrams tank is a third-generation battle tank that, like the Leopard, has a 120mm cannon.
The US Army's preferred battle tank, the M1 Abrams has a range of about 430km and a maximum speed of 67kph. Similar to the Leopard 2, the M1 Abrams is operated by a four-person crew.
But unlike the German-made machine, the M1 Abrams relies on a 1,500 horsepower gas turbine engine, which is capable of running on petrol, jet fuel or diesel.
The Pentagon has cited the different types of fuel as a reason why Leopard tanks are the easier of the two vehicles to provide to Ukraine.
The 55-tonne tank is protected by special armour made of steel and ceramic tiles. One of the features of the tank is the inter-vehicle information system, which enables automatic and continual exchange between vehicles.
In service with the British Army and the Royal Army of Oman, the Challenger 2 is designed for use in direct-fire zones.
Unlike the Leopard 2 and Abrams models, the Challenger has a 120mm rifled gun and has a range of up to 500km. It is also armed with a 7.62mm chain gun and a 7.62mm machine-gun.
The Challenger is powered by a 1,200 horsepower diesel engine and moves at a top speed of 56kph. It weighs 62.5 tonnes, with the option to have additional armour fitted.
British forces have used the Challenger 2 in Bosnia, Kosovo and Iraq.