Ukrainian soldiers stand on their armored personnel carrier (APC), not far from the front-line with Russian troops, in Izyum district, Kharkiv region on April 18, 2022.Ukrainian soldiers stand on their armored personnel carrier (APC), not far from the front-line with Russian troops, in Izyum district, Kharkiv region on April 18, 2022.

Russia's new offensive in the Donbas region could prove to be extremely significant and decisive in the war, analysts warn, and could determine how the country's territorial boundaries look in weeks and years to come.

The Russian war machine in the east could be a very painful threat for Ukraine, according to the Foreign Policy Research Institute.

It's clear that Russia's war aims remain quite extensive, and how the battle for Donbas proceeds will determine how much of Ukraine east of the D.

I think it's pretty clear that annexation is Putin's long term goal.

Russian officials have stated that their main objectives in this new phase of the war are complete liberation of the two republics of Lu. Most analysts believe that the Donbas region will be annexed by Russia.

Moscow has fomented the sentiment of the region's rebels over the last eight years, although it denies supporting them.

Russia's long-awaited offensive in the east appeared to begin in earnest on Monday with Ukrainian President Volodymyr Zelenskyy saying that the battle for Donbas was underway.

By Tuesday morning, Russia's defense ministry claimed to have hit more than 1,200 targets in Ukraine, and there were reports of rocket and artillery fire in eastern Ukraine. According to officials, Russian forces have taken control of the city of Kreminna in the Luhansk region.

In an intelligence update, the U.K.'s defense ministry said that Ukrainian forces were repelling attempts by Russia to take control of the eastern Donbas region.

After Russia pulled back many of its troops from areas around the capital Kyiv and other northern parts of the country, the focus has been on eastern Ukraine. The Pentagon believes that Russia has increased its fighting power in eastern and southern Ukraine with more battalion groups moving to the area last weekend.

The new phase of Russia's invasion was discussed in a video call with a number of countries, including the U.S. and U.K., which promised to send more weapons to Ukraine.

It's not a big deal how quickly any new weapons will reach Ukraine, but there are concerns that the war-torn country could struggle to re-arm itself quickly in the east.

Sam Cranny-Evans, a research analyst at the British defense think tank RUSI, told CNBC Tuesday that there was much uncertainty over how the battle for Donbas will progress, and that both sides will deplete their materiel over the last two months.

The battle is going to last a long time, I think, with both sides demonstrating their staying power.

There are a few questions surrounding the availability of bullets for the Ukrainians and that can become a problem in the opening phases of mass bombardment. If you don't have the weapons to return fire against those kinds of things, they do have a dramatic psychological effect and a physical effect.

He noted that Russia was probably on a limited clock in terms of what it could do with its personnel and material capabilities.

The Russians have spent a lot of missiles in this war, which will be hard for them to replace.

Tanks of pro-Russian troops drive along a road during Ukraine-Russia conflict in Ukraine April 17, 2022.

Cranny-Evans said it's not impossible to see a situation in which the Ukrainians can push back against the Russians in Donbas.

If they can organize and equip their troops adequately, they may be able to do that. Some analysts are cautiously optimistic that Ukraine might even be able to win this war.

It's hard to gauge what Putin's ultimate objectives are in Ukraine, so it's hard to assess how significant the battle of Donbas could turn out to be.

Cranny-Evans noted that the big question remains if Putin has abandoned his goal of liberating the Donbas.

If Russia annexes the region, there could be a difficult price to pay for Ukraine. It will be difficult to define the winner and loser of the war because of the destruction seen in Ukraine.

Is it really a victory for the country of Ukraine if it loses all of Donbass? Does it mean that peace will last forever? Will Ukraine have to fight another war in 10 years? Cranny-Evans said there is a lot of stake for the Ukrainians.

Ukrainian civilians and soldiers who lost their lives during the war with Russia are buried in the cemetery in Irpin, Ukraine, on April 18, 2022.

According to the Institute for the Study of War, Russia's offensive is unlikely to be more successful than previous Russian offensives.

The think tank noted that Russian forces had not taken the necessary pause in their operations to properly integrate units that had been withdrawn from northeastern Ukraine.

The Russian military has few, if any, cohesive units not previously deployed to, and the Russian forces have been patched up and filled out with soldiers from other damaged units.

The effective combat power of Russian units in eastern Ukraine is a fraction of their on-paper strength.

The institute noted that while Russian forces could wear down Ukrainian positions through heavy concentration of firepower and sheer weight of numbers, this would come at a high cost.