Ukrainian officials have warned the country’s residents that the battles with Russian troops are likely to intensify this weekend, in the lead-up to Russia’s Victory Day celebrations Monday, commemorating the 77th anniversary of the Soviet victory over Nazi Germany.

The holiday is celebrated across Russia with military parades.

Reuters reports that Russian President Vladimir Putin will send a “doomsday” message to the West on May 9.

A Russian Foreign Affairs Ministry spokesman said Friday that Russia has no intention of deploying tactical nuclear weapons to Ukraine.

“Russia firmly abides by the principle that there can be no victors in a nuclear war, and it must not be unleashed,” Alexei Zaitsev said.

Ukrainian officials from the country’s national security council said Friday that Victory Day could mean more shelling in parts of Ukraine.

“Since Russian troops cannot boast of any significant achievements on the front by Victory Day, the risk of massive shelling of Ukrainian cities these days is increasing,” the officials wrote on Facebook.

Ukraine has warned its citizens to take cover when they hear air raid sirens and to avoid large gatherings because of the expected uptick in Russian attacks.

By Saturday morning, however, Putin’s forces had still failed to seize control of the steel plant in Mariupol from Ukrainian fighters.

More civilians were rescued from the tunnels under the plant Friday, as the Ukrainians holed up at the sprawling complex made a stand to prevent Moscow’s complete takeover of the strategic port city.

Ukrainian Deputy Prime Minister Iryna Vereshchuk said 50 civilians were evacuated from the plant Friday. Eleven of them were children, according to the Russian Interdepartmental Humanitarian Response Center.

Mariupol is a city reduced to ruins by the Russian onslaught. About 2,000 Ukrainian fighters, by Russia’s most recent estimate, are holed up in a vast maze of tunnels and bunkers beneath Azovstal steelworks and they have repeatedly refused to surrender.

Local authorities in Mariupol accused Russian forces Friday of firing on a car traveling to evacuate civilians from the vast steel works, killing a fighter and violating a cease-fire agreement, Reuters reported.

The White House said Friday that U.S. President Joe Biden and other G-7 leaders will have a virtual meeting Sunday with Ukrainian President Volodymyr Zelenskyy.

The United Nations Security Council adopted a unanimous resolution Friday in support of a diplomatic solution to the crisis in Ukraine, the first such statement from the Security Council since Russia invaded Ukraine February 24.

As the drama in Mariupol continued to unfold, Pope Francis Friday called the war in Ukraine “barbarous” because of the Christian-against-Christian nature of the conflict. He made the comment to members of a Vatican office that promotes Christian unity among Catholics, Orthodox and other Christian churches.

The U.N. Food and Agricultural Organization said there are signs Russia is stealing grain from Ukraine.

“There’s anecdotal evidence that Russian troops have destroyed storage capacity and that they are looting the storage grain that is available. They are also stealing farm equipment,” said Josef Schmidhuber, deputy director of the FAO Trade and Markets Division, speaking to reporters Friday in Geneva.

U.S. first lady Jill Biden arrived Friday at Mihail Kogalniceanu Air Base in Romania to start her European visit to show support for U.S. troops and Ukraine. After visiting Romania, she will head to Slovakia, where, on Sunday, she will meet with displaced Ukrainian families.

Some information for this story came from The Associated Press, Agence France-Press and Reuters.