According to observers, Russia is beefing up its forces for a new assault on Ukraine’s eastern Donbas area, laying the stage for a lengthy struggle that would inflict huge losses on both sides as the Russians try to surround Ukraine’s fighters.

Military specialists are hesitant to predict who will win the struggle for Ukraine’s industrial heartland of Donbas, a key conflict that will almost certainly be severe and will eventually determine the path of the war.

“The conflict might result in both sides being pummeled to the point where neither can execute an assault or a counter-offensive,” said Konrad Muzyka, head of the Poland-based Rochan consultancy.

“Ukrainians will fight to the death for their country. Significant losses will be incurred by the Russians.”

According to him, an unsettling “frozen” confrontation might form and endure for months, with the continual fear of a new Russian invasion. Russia portrays its February campaign as an unique operation to undermine Ukraine’s military capability and weed out dangerous nationalists.

A protracted battle would frustrate any hopes that President Vladimir Putin has of declaring a significant victory in time for May 9 when Russia marks victory over Nazi Germany in World War Two with a huge military parade that the Kremlin leader oversees every year.

Ukraine’s troops have held on more robustly in Donetsk, which together with Luhansk makes up Russian-speaking Donbas, a swathe of which was seized by Russia-backed separatists in 2014. A significant Ukrainian contingent has been dug in since then.

Moscow might try to smash through Ukraine’s eastern border by moving troops, tanks, and armored vehicles in a pincer operation from the north and south. According to the experts, this would attempt to outflank and encircle Ukrainian soldiers from behind.

Analysts believe Ukraine would try to avoid open tank clashes by employing artillery to target supply lines and equipment and sending raiding squads to assault convoys and logistical lines.