US Vice President Joe Biden Tuesday lashed out at growing anti-Semitism in Ukraine, speaking in Kiev amid rising tensions in the country’s east between Ukrainians and pro-Russian separatists.

Addressing a reported uptick in anti-Jewish actions in Ukraine, including a flyer distributed in the eastern city of Donetsk calling on Jews to register with pro-Russian authorities, Biden said the US condemned any threat or attack on the Jewish community in Ukraine.

“Just as corruption can have no place in the new Ukraine, neither can anti-Semitism or bigotry,” said Biden, standing alongside acting Ukrainian Prime Minister Arseniy Yatsenyuk. “Let me say that again, neither can anti-Semitism or bigotry. No place. None. Zero. The United States condemns in the strongest possible terms all threats and attacks against Ukrainian Jewish communities as well as Roma and others, as you do, as well, I know, Mr. Prime Minister.”

In his remarks, Yatsenyuk did not address anti-Semitism or attacks on Jewish institutions, making do with a broader reference to meeting “the highest standards of protecting human rights and the rights of citizens.”

Biden also warned Russia on Tuesday that “it’s time to stop talking and start acting” to reduce tension in its neighbor to the southwest, offering a show of support for the besieged nation as an international agreement aimed at stemming its ongoing crisis appeared in doubt.

Several areas in eastern Ukraine, where many millions of ethnic Russian live, have seen separatist rioting against the Ukrainian government, which came to power last month after the ousting of former president Viktor Yanukuvych in a revolution that erupted over his perceived pro-Russian policies.

Since the revolution erupted in November, Ukraine, which has relatively low levels of anti-Semitic violence, has seen several serious attacks, including a stabbing and the attempted torching of two synagogues, most recently last week in Nikolayev.

The Ukrainian government and Russian government officials, as well as their supporters in Ukraine, have exchanged allegations of anti-Semitism.

In Donetsk, three unidentified men last week handed out anti-Semitic flyers calling on Jews to register with authorities and pay a special fee for what the flyers’ authors called Ukrainian Jews’ pro-Ukrainian sentiments.

Separatist leaders have denied any involvement in the distribution of the flyers, calling them a provocation.

Biden called on Moscow to encourage pro-Russia separatists in eastern Ukraine to vacate government buildings and checkpoints, accept amnesty and “address their grievances politically.”

Biden said Russia needs to act “without delay,” adding, “We will not allow this to become an open-ended process.”

Yatsenyuk was harsher in his characterization of Russia. “No country should be able to behave like an armed bandit,” he said. “Russia should stick to its international commitments and obligations. They should not behave as gangsters in the modern century.”

The warnings for Russia from both leaders demonstrated the fragility of last week’s multinational agreement.

Biden also announced the United States would provide an additional $50 million to help Ukraine’s beleaguered government with political and economic reforms.

The money includes $11 million to help conduct the May 25 presidential election, including voter education, administration and oversight. It also will help fund expert teams from U.S. government agencies to help Ukraine to reduce its reliance on energy supplies from Russia. Other technical advisers will help fight corruption.

The White House also announced $8 million in nonlethal military assistance for the Ukrainian armed forces, including bomb-disposal equipment, communications gear and vehicles.

In the most high-level visit of a US official since the crisis erupted, Biden met privately with Yatsenyuk and acting Ukrainian President Oleksandr Turchynov. He also met with democracy activists and spoke to TV cameras to tell the people of eastern Ukraine he had urged the nation’s leaders to keep reaching out to them.

“I know the men and women who hide behind masks and unmarked uniforms, they do not speak for you,” he said. “All are welcome as equals in shaping a new Ukraine. We count on you to be the voice for rights and freedoms.”

Biden paid tribute to the protest movement by visiting St. Michael’s Golden-Domed Monastery, perched on a hill a few blocks from Kiev’s Independence Square that was the site of massive demonstrations against then-president Yanukovych. The monks provided refuge to protesters fleeing riot police and served as a field hospital to treat demonstrators who were shot in the square. Some died from their wounds beneath the monastery’s high, blue bell tower.

“These heroes remind us of the true cost of a better future and the nobility of those who reach for it,” Biden said.

Earlier, he told leaders from various political parties that he brought a message of support from President Barack Obama as they face a historic opportunity to usher in reforms.

“The opportunity to generate a united Ukraine, getting it right, is within your grasp,” Biden said. “And we want to be your partner, your friend in the project. And we’re ready to assist.”

Biden spoke to nine Ukrainians in a hearing room with gilded moldings at the parliament, or Rada, as the media looked on. The group included three candidates running for president in the May 25 election — most notably billionaire chocolate magnate and front-runner Petro Poroshenko. Biden told the candidates he hopes that they have more luck than he did in two presidential runs.

Senator John McCain, who recently visited the region, described US allies in Eastern Europe as “extremely nervous” about the intentions of Russian President Vladimir Putin. In an MSNBC interview, the Arizona Republican called on Obama to give the Ukrainian government “some weapons to defend themselves.”

McCain, the ranking Republican on the Senate Armed Services Committee, said America must show more support for countries under siege. That doesn’t mean the United States “must fight” every war, he said, but “the only thing that Putin understands is a strong, viable alliance.”

Biden’s visit comes at a critical time, days after a tenuous international agreement was reached to de-escalate violence in eastern Ukraine, where pro-Russia insurgents oppose the government in Kiev.

“You face very daunting problems and some might say humiliating threats that are taking place indirectly,” Biden told the Ukrainian lawmakers.

He said the United States is an example of people from different cultures united as one nation, although he said Ukraine has a big difference. “We’re not sitting against a border of another powerful nation,” Biden said.

Biden told the lawmakers a priority for the US is to help them become independent from Russian energy supplies. “Imagine where you’d be today if you were able to tell Russia, ‘Keep your gas,'” Biden said. “It would be a very different world you’d be facing today.”

Biden said they have an historic chance now that Yanukovych has fled the country.

“To be very blunt about it, and this is a delicate thing to say to a group of leaders in their house of parliament, but you have to fight the cancer of corruption that is endemic in your system right now.” He mentioned reforming the courts and finding the right balance of power between the president and Rada.

He added: “I do not underestimate the challenge that you all face. And I do not underestimate the frustration you must feel when someone like me comes along and says this is a great opportunity for you.”

JTA contributed to this report