When Liev Schreiber first encountered how ordinary Ukrainians on the ground are handling the vast and urgent crises brought on by the Russian war, he says, one thing was clear to him immediately: “They were doing all the work.”

Speaking about his non-profit BlueCheck Ukraine at the Karlovy Vary Film Festival on Saturday, the actor/writer/producer explained this realization is central to his newly organized efforts to help.

Schreiber was also motivated to found BlueCheck Ukraine after hearing many Americans express doubt about whether funds donated to the war relief effort would reach those most in need. Westerners are skeptical about transparency in Eastern Europe, he learned, likely because of the region’s history of corruption and waste.

So he met with experts with organizations on the ground and they decided that donors needed an organization that could certify dollars given would be used effectively – something many large non-profits cannot do because they simply hire local subcontractors to distribute aid.

Knowing the facts in such a fast-changing environment is crucial, Schreiber added. “Chaos and misinformation – this is something Putin’s counting on.”

Another instant insight he’s gained since dedicating himself and a few friends to organizing help, said Schreiber, is that responding to the needs of those upended by war “is a moving target.”

Initially traveling to Poland to help chef José Andrés’ World Central Kitchen organization to feed some of the millions of Ukrainian refugees, he explained, his team was perplexed shortly after Easter this year when the crowds of migrants dropped from 10,000 a day to 900 or so.

It was clear many Ukrainians were headed back home, even though missiles were – and are – still hitting cities there far from the front lines. Another important lesson, then, is that urgent need may be hungry refugees coming from Ukraine one day, then transport for orphans inside the country the next. Or medical aid. Or shelter for the internally displaced.

Without quite telling his family, at least until afterward, Schreiber said, he then ventured into Lviv in western Ukraine to get a better sense of what was needed. He soon learned of a small group of taxi drivers and volunteers who on their own had shuttled some 10,000 children and women out of dangerous areas under Russian shelling. “Ukrainians are incredibly resourceful,” he said.

On the subject of whether film festivals should screen work that was funded by the Russian state, as Karlovy Vary, Cannes and other festivals have done this year, Schreiber said he’s “uncomfortable” with the idea of banning artists but added that the issue is a complex one without a clear right or wrong answer.

The star of “Ray Donovan” confessed that having discovered he had ancestral roots in Ukraine, he always felt a bit like he identified with the country. But after Russia invaded on Feb. 24, Schreiber said he realized quickly Americans “sitting on their asses” at home have very little real shared identity with what Ukrainians’ daily lives are now.

Still, shared roots do motivate people, he said. “I see America as a nation of grandchildren.”

Schreiber admits that it’s been a scramble setting up BlueCheck Ukraine, admitting even their website is still under construction. But he was inspired by speaking with Ukrainian president Volodymyr Zelensky. One thing the determined commander-in-chief imparted has stuck with Schreiber, he said: “You’re much more courageous than you think you are.”

The other insight he shared – which helps explain why taking action now is so urgent, was this: “It’s better to deal with this now before it comes knocking at your door.”

Schreiber, back at Karlovy Vary after 18 years, was last here to present his directorial debut, “Everything Is Illuminated,” starring Elijah Wood. The Golden Globe-nommed actor will speak to audiences Sunday at a masterclass about his film and TV work, likely touching on his roles in films such as “The Sum of All Fears” and “X-Men Origins: Wolverine.”