In a video conference on Tuesday, Allied leaders from around the world discussed Russia’s new invasion phase. A number of countries including the U.S. (and U.K.) promised to send additional artillery systems and weapons to Ukraine, while other nations, such as Germany, promised more money for Ukraine to buy more weapons.

It is unclear how fast any new weapons reach Ukraine. There are concerns that Ukraine could be unable to quickly rearm in the east given Russia’s increased frequency of attacks on ammunition depots.

CNBC’s Tuesday interview with Sam Cranny Evans, an analyst from the British defense think-tank RUSI, revealed that the future of the Battle for Donbas is uncertain. He said that both sides had exhausted their materiel over the past two months. However, Ukraine may be more at risk.

“I think that the one thing I feel most comfortable saying is this: [the battle]Both sides have shown “staying power” and will last for a long time, he said.

There are some questions about the supply of ammunition to the Ukrainians, which can be a problem especially during the initial phases of airstrikes and mass artillery bombardment. They have both a psychological and physical impact on those who don’t possess the ammunition to fire back at them.

He noted, however, that Russia was also “probably on an extremely limited clock” in terms of its human capabilities and its material capabilities.

He said that “The Russians have expended an awful lot missiles in war so far,” which it will be very hard to replace.

Cranny-Evans stated that it is possible to see a scenario in which Ukraine can push back against Russia in Donbas. This would be similar to what they have proven to be able to do elsewhere.

If they are able to organize their forces and can properly train them, then they might be capable of winning the war. Some analysts believe that Ukraine may even win the war. “A lot of this depends on the next phase and will determine which side wins,” he said.

Analysts find it difficult to judge how important the battle of Donbas will be within the wider war. This is because it is hard to understand Putin’s ultimate goals in Ukraine.

RUSI’s Cranny Evans noted that Putin is focusing its attention on the mission of “liberating” Donbas and has lost his “maximalist goal” to change the regime in Ukraine. Or, if it may accept a less significant victory in the east.

According to him, Ukraine may have to pay a high price for losing the Battle for Donbass and Russia annexes this region. Between the immense destruction in Ukraine and the ongoing war, it will not be easy to determine who is the victor or loser.

“[You could say]Ukraine won, its country is still there. But, if Donbass disappears completely from Ukraine’s hands, does that constitute a victory? Is it a guarantee that peace can last forever? Is it possible that Ukraine will have to fight another conflict in 10 years? Cranny Evans said that the Ukrainians have a lot at stake.

According to the U.S.-based Institute for the Study of War, Monday’s assessment of the future conflict phase showed that Russia’s military offensive was unlikely to prove more effective than the previous Russian ones. However, it cautioned that their forces may not be able to defeat Ukrainian defenders and make only limited gains.

It was noted by the think tank that Russian forces have not been able to take an “operational restraint” in order to properly integrate and reconstitute units damaged from operations in east Ukraine.

It stated that the Russian army has very few cohesive units and no units previously sent to Ukraine for new operations.

The Russian military’s effectiveness in fighting in Eastern Ukraine has been reduced to a fraction of its on-paper strength, according to the report.

According to the institute, while Russian forces can be used to destroy Ukrainian positions by “heavy concentrations of firepower” and “simply weight of numbers”, this will come at “high cost”, and a rapid and spectacular Russian offensive victory is highly unlikely.