Rabbi Moshe Hauer, the executive vice president of the Orthodox Union, said the organization had so far collected “many hundreds of thousands of dollars” in donations, most of which went toward helping people flee Ukraine.“Renting a bus, which would have been $700 a month ago, is running north of $15,000 now,” he said. “The bus rides are taking many, many times the normal amount of time to get from Point A to Point B because they have to find roads that are passable and bridges that aren’t blown up.”Orthodox Jewish leaders said that many in their community were especially concerned about the war because of Ukraine’s place in the history of Hasidic Judaism.The Hasidic movement, an ultra-Orthodox branch of Judaism, was founded in Western Ukraine in the 18th century and today has tens of thousands of adherents in New York City.Hasidic religious sites in Ukraine, like the grave of Rebbe Nachman of Breslov in the town of Uman, draw tens of thousands of pilgrims every year, making it a place that many find both familiar and holy, Rabbi Becker said. “People who don’t have any family ties to Ukraine at all still go to visit these Hasidic sites,” he said.Mr. Kliger, of the American Jewish Committee, estimates that 40 percent of the immigrant community in New York City is originally from Ukraine, 35 percent is from Russia, and the remainder are from smaller countries like Belarus or Moldova.Russian is a commonly spoken first language in the community, and it is the mother tongue of President Zelensky, he said. In years past, many Jewish New Yorkers who spoke Russian did not object to being described as “Russian Jews,” even if they were from Ukraine, Mr. Kliger said.