The imminent arrival in Ukraine of Western-made light tanks and armoured vehicles, as well as possibly heavy tanks, means Kyiv will need to quickly train up troops to use and maintain the sometimes-complex equipment, analysts say.
Ukraine's European allies have sent Kyiv more than 300 modernised Soviet tanks since Russia invaded more than 10 months ago.
But they have so far held off on dispatching the Western-made heavy tanks that Ukraine has repeatedly requested to push forward against Russian invaders.
Near the battleground city of Bakhmut in eastern Ukraine, Ukrainian captain Volodymyr Tchaikovsky said NATO tanks had "a huge advantage" for any soldier inside.
"If he has the coordinates of his target, he can destroy the target with one shot," the 54-year-old said.
Initial reluctance to provide Ukraine with advanced weaponry seems, however, to be lifting.
Poland on Wednesday said it was willing to send Kyiv 14 advanced Leopard 2 battle tanks as part of an international coalition.
The German-made model is largely seen as one of the best-performing worldwide and is widely used across Europe, meaning spare parts and ammunition are readily available.
But Germany has so far refused to give its necessary green light to the delivery, fearing an escalation that would more directly pit the West against Russia.
Finland on Friday said it was not opposed to any shipment of Leopards, after a discussion with European countries who have them.
"(But) this requires not only the transfer of the material itself, but also training and the creation of the necessary maintenance and servicing expertise in Ukraine," Finnish defence ministry official Tarja Jaakkola told AFP.
Britain has not ruled out providing Challenger 2 battle tanks.
And a meeting of Ukraine's allies in Germany on January 20 could see Western nations make new pledges.
- 'Logistical headache' -
Last week, France, Germany and the United States opened the way with promises of French AMX-10 RC light tanks, 40 German Marder infantry vehicles, and 50 Bradley fighting vehicles.
A French source said Paris could dispatch around 40 of the highly mobile AMX-10 RCs, which are wheeled rather than tracked but have a much heavier cannon typical of a tank.
The French defence ministry said late on Thursday that a first batch would be delivered "within two months".
Once all the foreign gear arrives, Kyiv will have to bring its military personnel rapidly up to speed with how to handle and fix it.
"That equipment is one thing. Using the equipment is another," a US military official said.
Analysts agree that the Ukrainians have so far shown a remarkable ability to adapt to the various military instruments that have flooded in since the Russian invasion on February 24, 2022.
Before that date, Ukraine had around 900 Soviet-era tanks.
"Soviet tanks are very crude. There are fewer electronics on board," said a French officer, who asked not to be named.
"In view of the diversity of the pledged Western tanks and armoured vehicles, it's bound to be a logistical headache for them," he added.
"The range is extremely broad. Each has its own weapons system, its engines."
The tanks also require highly specific munitions.
The German Leopard 2 fires 120-mm artillery shells.
The British Challenger 2 comes with a 120-mm rifled gun that requires specific ammunition.
The French AMX 10 RC is less complex to manoeuvre than a heavy tank but uses 105-mm ammunition.
- 'Poisoned chalice'? -
With fighting at some of its most intense between Ukrainian and Russian troops, all military gear needs to be in the best possible shape.
Leo Peria-Peigne, a weaponry expert at French think tank IFRI, said Ukraine had "a considerable pool of labour" and the structures in place to "assimilate all this diverse equipment".
Army personnel deployed near the front line can usually fix the lighter damage, but heavier repairs are typically undertaken further away from the fighting.
Ukraine's allies have already started organising maintenance so all newly delivered gear remains operational.
French-German defence industry firm KNDS, for example, in November opened a maintenance hub in Slovakia to repair military gear such as the Caesar howitzer artillery and Gepard anti-aircraft systems sent to the battlefront.
But Peria-Peigne warned it would be crucial for the West to send enough tanks and armoured vehicles to Kyiv for all the training and maintenance efforts to be worth it.
"A battle tank is the most complex of military vehicles in terms of maintenance on land," he said.
Usually a third of all tanks in a battle situation are in maintenance at any one time.
"The United Kingdom sending just 10 Challenger 2 tanks would be a poisoned chalice," Peria-Peigne said.
"It would require drawing up a whole training and maintenance scheme for a very limited availability (of tanks) and therefore minimal effect on the ground."