AMNA NAWAZ: Poland has been one of Ukraine's staunchest supporters since the full-scale Russian invasion.

But many of its people are slowly turning against the one million Ukrainian refugees given sanctuary over the last four-plus years.

Divisions between Poles and Ukrainians are being exacerbated by bitter cultural memory of a World War II massacre, as special correspondent Malcolm Brabant reports from the Polish capital of Warsaw.

MALCOLM BRABANT: Warsaw's Central Station in March 2022 two weeks after the Russian invasion of Ukraine, the concourse was packed with refugees fleeing the war; 4.5 years on, nearly a million Ukrainian refugees remain here.

Only Germany provides sanctuary for more.

After enduring the war for a month, Natalia Klimenko escaped to Poland with eternal gratitude.

NATALIA KLIMENKO, Ukrainian Refugee (through translator): When I came, do you understand, I still can't talk about it without crying.

They welcomed us as if we were family.

I was stunned by this welcome, like relatives on the border.

MALCOLM BRABANT: What a difference four years makes.

In 2022, when Russia invaded Ukraine, 94 percent of all Poles were in favor of welcoming Ukrainians fleeing the front lines.

But now, according to the latest public opinion survey, more than half the nation, 52 percent, to be precise, oppose the idea of giving sanctuary to those running away from the war.

Occasionally, Polish antipathy towards Ukrainians escalates to violence.

This couple was attacked after their assailants heard them speaking in their native tongue.

Dmytro Dymydyuk mans a hotline at a Ukrainian help center.

So palpable is the hostility in Warsaw that he maintains a very low profile.

DMYTRO DYMYDYUK, Coordinator, Ukrainian House Foundation: I try not to use social media.

I don't write any comments.

I don't take part in this holy wars in social media.

So I just try to live normal life, job, house, shops, et cetera.

So I try to avoid any places, any manifestations where someone from Polish side can attack me.

NATALIA PANCHENKO, President, Stand With Ukraine: Last few months, we have every month more and more calls, when people are calling us, and they need support because they are victims of hate crimes.

MALCOLM BRABANT: Natalia Panchenko, president of a nonprofit called Stand With Ukraine, blames extremist politicians.

NATALIA PANCHENKO: The role of politicians is very important on everything which I'm talking to you about, because hate speech or hate crime is a result.

First, politicians start to show Ukrainian community in Poland as someone very bad.

GRZEGORZ BRAUN, Leader, Confederation of the Polish Crown: Polish crown This is Poland.

This is not some Ukropole.

MALCOLM BRABANT: Grzegorz Braun is an ultra-right politician who is not easily ignored.

In the 2025 presidential election, he surprised his critics by winning 1.2 million votes.

GRZEGORZ BRAUN: With people coming from other countries, we get social diseases, and not only social diseases.

As a bonus, we get costs.

MALCOLM BRABANT: Braun shocked Poland during a sacred Jewish holiday when he extinguished a menorah in the Polish Parliament.

Braun is brazen about his antisemitic beliefs and hatred for what he calls the Ukrainization of Poland.

But isn't it the decent thing to do as a neighbor to offer sanctuary to your neighbors when they're under threat from one of the most powerful militaries in the world?

GRZEGORZ BRAUN: OK.

OK, is it a decent thing to do having a neighbor in trouble with problems making a hole in Europe, house's wall, and inviting your neighbor with his problems, probably giving him your wallet and all the keys to your apartment, your car?

It's not a decent thing.

MALCOLM BRABANT: Such rhetoric has contributed to a Ukrainian exodus.

In the past six months, over 100,000 have left Poland.

NATALIA PANCHENKO: Unfortunately, yes, it's true.

Some people can't feel here safe, and they are leaving our country and going to different countries.

Some of them even come back to Ukraine, Ukraine, which is still under attacks every day.

MALCOLM BRABANT: Behind the scenes, Moscow is suspected of stirring the pot of resentment.

FILIP BRYJKA, Polish Institute of Foreign Affairs: Obviously, Russia is the main beneficiary of this -- tensions between Poland and Ukraine.

MALCOLM BRABANT: Defense analyst Filip Bryjka specializes in Russian hybrid warfare.

FILIP BRYJKA: Since 2014, actually, Russia is holding long-term disinformation campaigns targeting Polish Ukrainian bilateral relations.

Mostly, those campaigns are related to the some historical disputes.

MALCOLM BRABANT: In Warsaw, activists are reminding people of the slaughter of 100,000 Poles in the region of Volhynia 83 years ago.

The pogroms, labeled genocide by the Poles, were carried out by Ukrainian ultranationalists.

They were led by Stepan Bandera, who, during the Second World War, collaborated with the Nazis in the fight against Stalin's Soviet Union.

JAN DARASZ, Historian: The Ukrainian paramilitary surrounded defenseless villages, dragged out the men, women and children, massacred them using farm implements, axes, scythes, hammers, that sort of thing.

The houses were looted and burnt.

MALCOLM BRABANT: Jan Darasz is a historian and journalist with Polish television.

JAN DARASZ: History matters in Poland.

It's very comparable to what we saw in Rwanda.

MALCOLM BRABANT: Ukraine's President Volodymyr Zelenskyy has aggravated Polish sensitivities by naming a contemporary military unit after the Second World War Ukrainian insurgent army, Stepan Bandera's militia.

Zelenskyy was stripped of Poland's highest state honor as a result.

Poland's president, Karol Nawrocki, branded Zelenskyy's decision an outrageous glorification of historical atrocities.

It may have been Zelenskyy's intention to honor the insurgent army's fight against the Soviet Union, but Poles don't see it that way.

Activist Pawel Kryszczak: PAWEL KRYSZCZAK, Anti-Bandera Activist (through translator): Since the wave of refugees from Ukraine arrived, we have seen an increase in the spread of vandalism, flags, or other symbols that simply clearly indicate a reference to the ideology that led to the death of hundreds of thousands of Poles in Volhynia.

MALCOLM BRABANT: In the past year, funerals have been held for about 100 massacre victims whose bodies were exhumed from mass graves.

But there are tens of thousands more victims who aren't awaiting a Christian burial, and whose murders aggravate the division between Ukrainians and Poles.

President Zelenskyy has shown no signs of reversing his decree and has doubled down, saying it's a matter of internal sovereignty.

JAN DARASZ: There's two views of the same problem, and I don't think it's capable of being resolved.

MALCOLM BRABANT: With sympathy and charity dwindling, Ukrainian refugees are hoping that the issues driving a wedge between the two countries don't become even more inflamed.

For the "PBS News Hour," I'm Malcolm Brabant in Warsaw.