Well, two years ago, Ukraine was on the brink of something few thought would happen, a full-scale Russian invasion. Today, much of Eastern Ukraine looks like this: buildings destroyed and the landscape ruined. And of course, lives have been changed forever. Ukraine's Western allies are urging the world to continue their support at a meeting of the United Nations Security Council in New York. Our correspondent, Andrew Harding, has returned to the east of the country. He's been following the story of one Ukrainian soldier, a medic working on the front line who he first met at the start of the conflict.

Two years of war seen through the struggles of one Ukrainian doctor. This was the first time we met Oleg Kravchenko back in 2022 in a besieged town called Lysychansk. Oleg had just joined Ukraine's army as a volunteer medic.

Look here.

He drove us to his unit near the front lines.

It's the same from Russia.

In those early days, a smiling Oleg was full of confidence. It's my country. But the Russians are pushing now. They're warming a lot.

I hope maybe one and a half months, and we will shoot every Russian.

You'll push them out?

Yes.

So you think you're winning this?

Yes.

But within weeks, the Russians had destroyed and captured Lysychansk.

It would be a year before we met Oleg again.

His medical team was now working in another frontline town, Bakhmut. Lots of casualties from Ukraine struggling counteroffensive. The danger's growing.

I'm still alive.

You're still alive, yes. Alive, yes. But it's been a difficult year.

Very difficult.

As if to prove the point, incoming fire. You're not worried about your safety.

My fate is... I don't know.

And now, two years into the war, we've come to meet Oleg's team once again. As usual, they're in the thick of it. This time in Kupyansk, another furious battle underway. Russia now inching forwards. The gunfire you can hear is Ukrainian troops trying to shoot down a suspected Russian drone. They heard it overhead. We've taken cover under some trees. Not sure if they've hit it yet.

.

The Ukrainians have found a new Russian target. But what of Oleg? We'd lost touch with him for several months, but now hear news of an attack last October. A Russian rocket hit the field hospital he was working in. Three medics were killed. But Oleg survived. His leg badly mangled.

My friend died. It's difficult. It was very difficult for me, and my mind is changed after that.

When we first met in Lysychansk, you were hopeful that Ukraine could win. When we met in Bakhmut, you were tired and worried, very tired. Now, how do you feel about the war? Can Ukraine win?

Yes, of course. I hope. But I think it's war will be long.

A long war then.

A medal of honor. It's from Zelenski.

And for Oleg, medals and an early retirement after two years that have transformed every life in this country. Andrew Harding, BBC News, Eastern Ukraine.

Our Chief International Correspondent, Lise Doucet, is in Kyiv tonight. Lise, you have been there throughout. You were there at the start of the conflict. Two years on, where does it go from here?

Well, it feels very different, as you just heard in Andrew's report. Two years ago, after Ukrainians recovered from the shock of Russia's full-scale invasion, they insisted to a person that this was a war. They can win and they would win. A year ago at this time, President Zelensky even said it would all be over by now. But now, Ukrainians are accepting this will be a long war. And even more, that Russia forces are now advancing in Eastern Ukraine from at least five directions. They're exploiting the delay in the deliveries of critical military support from its allies. Most of all, this $60 billion security package that's been held up in the US Congress by political infighting. On front lines, Ukrainian soldiers are exhausted, and they're running low on ammunition. Everyone I've spoken to here, from people in coffee shops to top security officials, are grateful for the aid from allies. But they're warning, they need military support now, saying that if President Putin wins in Ukraine, he won't stop in Ukraine.