North of Bakhmut, another key battle tests Ukraine

STORY: Battalion Commander Andrii, whose full name we can't disclose, is issuing orders into his radio at this command center in a location we also cannot disclose, except to say it's in a house in a bombed out village somewhere near the city of Kreminna in eastern Ukraine.

His call sign is "Tuman" which means fog. On the laptop screens near him two of his soldiers are looking at a drone view searching for Russian troops.

This is the Luhansk region of Ukraine. Kreminna is about 47 miles north of Bakhmut, where the bloodiest battle in Europe since World War Two is taking place. And although it may seem quiet in this forest, Tuman says he fears the same tactics and strategies being used by Russia in Bakhmut may be playing out here as well, but over a much wider area.

The Russians, they say, are sending waves of forces to attempt one giant pincer move.

"If they come to Lyman, then beyond there is Kramatorsk and Sloviansk. It will pose a 'pincer' threat which is why they are trying to fight for this area so heavily - this is no less important than Bakhmut.”

"I monitor, evaluate the situation, and make decisions 24/7. I inflict damage on the enemy with mine or my teams’ weapons. I conduct manoeuvres of my units to strengthen the frontline or for counter-offensive actions.”

In the drone unit in the woods, a serviceman call-signed "Zara" is talking about the Russians' use of electronic warfare. They have anti-drone guns. Some of the Russian countermeasures can also create what he called "domes" - which basically deny the Ukrainians from flying drones in an area.

"The Russians try to adapt in real time. This makes great problems for us, because we have to think a couple of steps ahead - how do successfully complete the mission and not let the enemy know how we did it."

The forest also presents other challenges. This soldier, call sign "Phoenix," is telling us that this is actually a Polish tank donated to Ukraine, and that it's been through several battles with his unit. But it's hard to drive in the forest, so they can't really use it like a tank... it's working as artillery instead.

Back in the command center, Tuman says Russian forces have attempted 40 or 50 assaults on his troops' defensive lines since early February.

His entire life has been consumed by war. He is from Chechnya and fought two conflicts there. He once retired from Ukraine's military in 2007 only to return in 2014 to fight Russian-backed separatists.

His only son was killed in fighting near the beginning of the invasion last year. He is also Muslim and lost one of his three wives around that time.

Now he fights for revenge.