Ukrainian forces fighting pro-Russian separatists have been holding positions in Donbas since 2014. They still hold the line, but now the sporadic clashes have turned into a full-blown war..

Lieutenant Denis Gordeev is accustomed to war, but not to this. " “We are bombed and rocketed every day, all the time, every hour.”.

Gordeev has been fighting Russian-backed separatists in the Donbas for eight years now, but now he and his men are facing the full might of the Russian army..

After retreating from Kyiv three weeks ago, Russia refocused its military operations on eastern Ukraine in order to seize the entire Donbass.. Many units of the Russian army have been deployed here.

According to Western estimates, Russia now has about 76 battalion tactical groups in the region, each of which has about 800 people..

According to Western experts, the Russian military took into account some of the mistakes made in the first phase of the war.. It also helped that now they are fighting on a shorter front and under a single command..

As a result, Ukrainian forces are struggling to hold a 300-kilometer front line in Donbas.. They have already lost some positions and are likely to lose even more in the coming days..

Russian forces conduct reconnaissance in force to find weaknesses in the defense of Ukraine.

While the Russian military is strengthening around the city of Izyum and around Severodonetsk and Popasnaya. Attacks are being conducted from several directions, although the Russians have not yet broken through the front.

Lieutenant Gordeev says he and his men are feeling the effects of the Russian regrouping.

The day before we arrived, one of his men was killed and five more wounded.. This is only a small part of the daily losses of Ukrainian forces, although there is no official data.. We tried to visit the nearest field hospital, but they didn't let us in, saying we were busy..

Can this be considered the beginning of a major operation of the Russian army, which has been talked about so much lately, or is it just a prelude to it

So far there is no obvious answer.. At the moment, the Russian army mainly uses artillery and rockets to break the Ukrainian defenses.. Some military analysts believe a major offensive is yet to come.

And Ukrainian forces, including Lieutenant Gordeev's unit, are holding out for now, even though Western experts say the Russian army is three times the size of the Ukrainian one..

They also acknowledge that Ukraine may have to cede territory in open spaces to defend key cities where it would be harder for the Russian army to attack..

I was allowed to visit the forward position of Lieutenant Gordeev during a short respite from the fighting.. At the command post, the soldiers built a semblance of a chapel and pray for victory. But this place does not look like a normal church - echoes of artillery salvos can be heard here.

On the way to his trenches, Gordeev reveals that mortar and sniper fire is a constant threat.. Their forward position is 600 meters from Russian troops.

The landscape is mostly open countryside with some shelter behind trees. Rare bursts of small arms are heard.

" And we don't know when they'll stop. We don't know when their journey will end," Before the war, he was a lawyer and hopes that one day he will be able to return to his former life.. But today, according to him, the main thing for him is victory in this war..

In the trenches, out of sight of the enemy, the mood is calmer, although the tension of recent fighting is clearly visible on the tired faces of the soldiers..

They show us some of their weapons: the Soviet heavy machine gun DShK, which is still used in conflicts around the world, and rocket-propelled grenade launchers..

These are mostly obsolete Soviet-made weapons, but they are proudly showing us their only Swedish-British man-portable anti-tank guided missile, the NLAW.

One of Lieutenant Gordeev's subordinates was trained by the British military to use NLAW shortly before the start of the war.. According to the lieutenant, they have already destroyed a Russian tank with such a missile..

" Russia, he said, is a militarized state, while Ukraine's ability to maintain its own weapons production is undermined.. Western supplies - or lack of them - will greatly affect the outcome of the war.

Lieutenant Gordeev claims that the morale of his troops is still high: they are defending the Motherland.

But President Putin needs at least something that can be called a victory, and as soon as possible - perhaps by May 9, for the Victory Parade.

Time is on the side of Ukraine - but only if the flow of Western weapons does not dry up, and the Ukrainian army is able to contain the offensive of Russian troops expected from day to day.

Jonathan Beal, BBC Defense Correspondent, Eastern Ukraine.