JOHN YANG: Along the Russia-Ukraine border badly stretched Ukrainian forces are struggling to deny Russia a foothold.

The town of Vovchansk just three miles inside the border has seen some of the fiercest fighting since Russia launched its offensive.

That's where John Ray of Independent Television News joined soldiers from Ukraine's 57th Brigade.

JOHN RAY, Independent Television News (voice-over): These are anxious times for Ukraine the specially for the better the 57th Brigade.

The shooting starts the moment we arrive.

It turns out they're hunting a drone that's hunting them.

There's danger from every direction at any time.

OLEG, 57th Brigade: They are striking everything.

Everything they can, they strike.

JOHN RAY (voice-over): Oleg is a new recruit.

And already an exhausted veteran.

OLEG: Everything is very difficult.

Very hard.

JOHN RAY: A lot of rockets a lot of drones.

OLEG: This is drones.

Drones like bees, like everywhere.

Only you hear -- what's frightening it's like rain.

Like rain.

JOHN RAY: Have you had any rest?

OLEG: No.

No.

JOHN RAY (voice-over): Then suddenly, his unit is called back to the action.

These men have been stretched to the limit.

The battlefield is a wasteland of streets by street fighting.

Vovchansk one soldier tells us exists now in name only.

This was a hospital leveled by Ukrainian missiles after Russian soldiers took up positions inside.

JOHN RAY: That is the sound of outgoing artillery.

The Russians have conquered this land once before.

And now Ukraine is having to fight for it a second time.

JOHN RAY (voice-over): Little more than a week ago.

This was a border now it's a battlefield.

The men here have been rushed to this new frontline leaving defenses elsewhere thin.

Deep in his bunker it's a fear shared by their commander.

DYMTRO, 57th Brigade, Ukraine (through translator): Yes, I really worry about that.

There are a lot of Russians, we need more of everything.

The front line was already very long.

Now it's even longer.

JOHN RAY: The Russians have punched a deep hole in Ukraine's defenses and these men are doing their best to fill it.

But they have been fighting almost without a break for more than two years.

And right now it's the Russians who are recovering their strength.

JOHN RAY (voice-over): Lives lost and lives abandoned.

This village has been hit four times.

They're just finished rebuilding the school after the last Russian occupation two years ago.

Now Roman is one of the very few civilians left.

JOHN RAY: They know what Russian rule means.

ROMAN SHVIGAL, Bugaivka Resident (through translator): Yes, yes.

We can see the Russians know how they still (inaudible) everything.

They take everything they can, but they're really shocked.

JOHN RAY (voice-over): They know there are more Russian troops further along this border ready to move along summer of fighting lies ahead.

JOHN YANG: That was John Ray of Independent Television News.