AMNA NAWAZ: Today, Ukrainian President Volodymyr Zelenskyy said that troops in Eastern Ukraine captured Chinese nationals fighting for Russia.

It's a reminder of that war's global impact.

Russia's full-scale invasion has certainly affected the thinking in Taiwan, which, like Ukraine, sees itself confronting a much larger neighbor that challenges its sovereignty.

Nick Schifrin reports now on the connections between Ukraine and Taiwan as part of our series "Taiwan: Risk and Resistance."

And a warning: Some images in this story are disturbing.

NICK SCHIFRIN: Outside Russia's diplomatic office in Taipei, in the shadow of Taiwan's largest building, there is cross-continental solidarity.

OLENA TREGUB, Ukrainian Secretary-General, Anti-Corruption Commission: In order to have peace, you need to prepare for war.

And this is what we were trying to tell to our Taiwanese friends here.

NICK SCHIFRIN: Olena Tregub is a Ukrainian anti-corruption advocate.

She says Ukraine should provide Taiwan inspiration.

OLENA TREGUB: No matter you have smaller army, no matter you have smaller economy, no matter you have less people in your population, it doesn't matter.

If people in your country are ready to resist, if they are free, if they are brave, it's impossible to take over a country.

NICK SCHIFRIN: They dress as prisoners of war to protest Russian war crimes.

It's a reminder of Ukraine's horrors, the subjugated, the slaughtered, the scorched, that 37-year-old Huang Yu Hsiang takes as omens.

HUANG YU HSIANG, Taiwanese Pro-Ukraine Protester (through translator): If Russia is not held accountable for its actions, China might think they can get away with it too.

We can't let that happen.

NICK SCHIFRIN: Jack Yao took that personally.

Why did you volunteer to fight in Ukraine?

JACK YAO, Taiwanese Volunteer Soldier in Ukraine: Simple reason.

Why not?

Because I want to do something and I want to help, especially we have a situation similar.

NICK SCHIFRIN: Why did it seem similar to what China could do to Taiwan?

JACK YAO: Culture and the history.

And they are all communists.

(EXPLETIVE DELETED) the communists.

NICK SCHIFRIN: Yao was a 28-year-old businessman when he decided to join Georgian troops fighting as part of Ukraine's Foreign Legion.

In Russia's full-scale invasion of Ukraine, he saw a larger military invading a smaller neighbor and claiming historic, cultural and linguistic ties, what Beijing could do to Taiwan.

He trained to help transport equipment and weapons.

Nothing prepared him for what he saw, the Russian destruction of Irpin, the Russian systematic killings of Bucha.

And what do you think when you think back to Bucha and Irpin?

JACK YAO: I think they are animals.

Only animal will do this.

Probably animal will not do this.

Who will do this?

Evil will do this.

NICK SCHIFRIN: Another Taiwanese soldier, Jonathan Tseng, also volunteered for Ukraine.

He never came home.

His mother clutched her memories and Ukrainian flag.

Jack Yao says, before Ukraine, Taiwanese were dreaming.

The war woke them up.

And the most important lesson, Taiwan must show Ukrainian determination to fight.

JACK YAO: When a war is coming or a situation is really coming, fighting back, let the people know we are not hiding and that we are prepared for this for long times and we are not afraid.

NICK SCHIFRIN: Do you think Taiwan is ready to be able to defend itself?

JACK YAO: Fifty-fifty.

If it were two years ago I will tell you zero.

But now I think it's 50/50,because now people, they know something's wrong.

NICK SCHIFRIN: But to get ready, Taiwan needs U.S. support.

DONALD TRUMP, President of the United States: You're gambling with World War III.

NICK SCHIFRIN: Which is why Taiwan was horrified when President Trump berated and temporarily cut off Ukraine from U.S. assistance and intelligence.

What's the lesson that Taiwan would take if the United States cut support for Ukraine?

JACK YAO: Will be chaos and hell and the people will -- losing hope.

But, still, we're fighting back, even we don't have a bullet.

This is also why I go into Ukraine.

If you don't want to do something first, why people help you?

Simple reason, yes.

This is our country.

You must prepare dying -- prepare to dying for your country.

NICK SCHIFRIN: Today, the enemies of Ukraine and Taiwan celebrate their connection.

Their partnership has -- quote -- "no limits," from expanded military training to cultural kinship.

Chinese schoolchildren sing Russia's most famous wartime hymn.

But as an axis of autocracies grows closer, so too does the feeling of a shared front line across two young democracies fighting authoritarianism.

That is perhaps personified in a Ukrainian restaurant in Southern Taiwan named Hata, or home, and its owner, Olga Kolish.

We spoke out front on a main street.

How do Taiwanese like the Ukrainian food?

OLGA KOLISH, Ukrainian Restaurant Owner: Yes, I think they enjoy it.

I also explain the difference, because although we have some similarities with Russian food, but we have some very eccentric dishes.

NICK SCHIFRIN: The authenticity is a family affair.

Those are Ukrainian dumplings made by the restaurant's chef, Kolish's Taiwanese husband, Lin Yua (ph), their children fluent in Mandarin and Ukrainian, and their restaurant resistance to Russia in mouth and mind, sunflowers, the symbol of Ukraine's resilience, snapshots of solidarity, including aid sent from Taiwan to Ukraine, and Ukrainian President Volodymyr Zelenskyy's words of defiance in Mandarin.

OLGA KOLISH: Taiwanese people should have that courage and be brave enough to protect their country.

The world is not peaceful anymore.

It's not safe anymore anywhere in the world.

So that also means any big country can occupy smaller countries.

So that is why I tell them all the time, you have to fight for yourself.

You have to sacrifice your people, yes, because it's your home.

AMNA NAWAZ: And Nick joins us now.

Nick, another terrific report in your series.

I want to return to something we mentioned at the top, though, Ukraine announcing today that they captured Chinese nationals on the front lines.

What more do we know about that?

How unusual is it?

NICK SCHIFRIN: So, Jack Yao, who we introduced to you in the story, the young Taiwanese man who traveled to Ukraine to fight, actually told me that he came across Chinese in Eastern Ukraine on the front line, and that was late 2022 when he was there.

So it is not unprecedented, but it is rare.

Today, President Volodymyr Zelenskyy posted this video you see, there saying Ukraine captured these Chinese nationals' I.D.s and ATM cards.

They speak a little English and suggest their commander was wounded or killed.

And Zelenskyy said Ukraine has information there are -- quote -- "many more Chinese citizens in the occupiers' units."

But U.S. officials tell me, Amna, there is no evidence that Beijing is sending civilians or soldiers to the front lines.

And so, therefore, the assumption is that any Chinese national who ends up there is simply a soldier of fortune.

But, as we know, as we have talked about for years now, the U.S. has assessed that China sends machine tools, microelectronics, and other items that have propped up Russia's defense industrial base and allowed them to continue to prosecute the war in Ukraine.

AMNA NAWAZ: All right, Nick Schifrin, thank you very much.

NICK SCHIFRIN: Thank you.