The transfer of F-16 fighter jets to Kyiv would raise the question of NATO's involvement in the conflict, Russia's ambassador to the United States said in comments published early Monday.
"There is no infrastructure for the operation of the F-16 in Ukraine and the needed number of pilots and maintenance personnel is not there either," Anatoly Antonov said in a statement posted on the embassy's Telegram channel on Monday.
"What will happen if the American fighters take off from NATO airfields, controlled by foreign 'volunteers'?"
The remarks come after US President Joe Biden on Friday endorsed a plan for training programs for Ukrainian pilots on F-16 fighter jets.
Ukraine's President Volodymyr Zelenskyy assured Biden that the jet would not be used to go into Russia's territory.
Meanwhile, Antonov also said that any Ukrainian strike on Crimea would be considered a strike on Russia.
"It is important that the United States be fully aware of the Russian response," he added.
Here are some of the other developments concerning Russia's war in Ukraine on Monday, May 22:
Bakhmut 'not occupied' by Russia: Zelenskyy
Ukrainian President Volodymyr Zelenskyy said that Bakhmut is "not occupied" by Moscow, even as the chief of Russia's Wagner mercenary group claimed that his fighters had seized control of the eastern salt-mining town "to the last centimeter."
"Bakhmut is not occupied by Russia today," Zelenskyy said on Sunday at a press conference on the sidelines of the G7 summit in the Japanese city of Hiroshima.
"I cannot share with you the tactical views of our military. The most difficult thing would be if there was some tactical mistake in Bakhmut and our people were surrounded."
Ukraine's military said that it was holding on to a small part of the city, which has been the site of the bloodiest fighting during Russia's war in Ukraine.
"We continue to advance on the flanks in the suburbs of Bakhmut," Oleksandr Syrsky, the commander of Ukraine's ground forces, said.
However, Wagner head Yevgeny Prigozhin said that there were no Ukrainian soldiers in Bakhmut.
"There is not a single Ukrainian soldier in Bakhmut as we have stopped taking prisoners," he said in a statement posted on Telegram. "There are a huge number of corpses of Ukrainian soldiers."
Prigozhin said that Zelenskyy was either not telling the truth or "like many of our own military leaders, simply does not know what is happening on the ground, this is a possibility."
He added that Wagner would hand over control of Bakhmut to the Russian army by May 25.
Zelenskyy likens Bakhmut's ruins to Hiroshima after WWII
President Volodymyr Zelenskyy likened the ruins of Bakhmut to the destruction of Hiroshima in World War II as he took part in the G7 summit in the Japanese city on Sunday.
"I'll tell you openly: Photographs of ruined Hiroshima absolutely remind me of Bakhmut and other similar settlements. Nothing left alive, all the buildings ruined," Zelenskyy said while talking to the media.
Following the comments, Russian Foreign Ministry spokesperson Maria Zakharova derided the Ukrainian president's comparison, saying the US bombed Hiroshima and is now providing military support to Ukraine.
"Nice one," Zakharova said on Telegram. "Since both were carried out by the White House."
Brazil's Lula 'upset' at not meeting Zelenskyy
Brazilian President Luiz Inacio Lula da Silva said on Monday that he was "upset" he and Volodymyr Zelenskyy did not meet at the G7 summit, adding that the meeting fell through because his Ukrainian counterpart was late.
"I wasn't disappointed. I was upset, because I'd like to meet him and discuss the matter," Lula told reporters at a press conference before heading home from Japan.
But "Zelenskyy is a grown-up. He knows what he's doing," Lula said.
He added that he did not see a point in meeting Zelenskyy now, saying neither he nor Russian President Vladimir Putin seemed to want peace.
"For now, they're both convinced they're going to win the war," he said.
Lula is pressing for peace negotiations and has proposed Brazil as a mediator, along with other "neutral" nations, including China and Indonesia.
However, he faced criticism last month after he accused the US of "encouraging" the war.
Russia launches overnight air attack on Dnipro — governor
Russia carried out an overnight air attack on the southeastern Ukrainian city of Dnipro, officials said.
The Ukrainian army said 16 missiles and 20 attack drones had targeted its troops and the city's infrastructure.
Local governor Serhiy Lysak said on Telegram that eight people were injured and that three of them were being treated in the hospital.
"Thanks to the defense forces, we withstood the attack. Details will come in due time," Lysak said, referring to Russian forces as "terrorists."
RBC-Ukraine news agency reported that around 15 blasts were heard during more than 90 minutes of air raid alerts.
But it wasn't clear if the sounds were air defense systems destroying targets or Russian missiles or drones hitting their targets.
With a Ukrainian counteroffensive looming, Russia has resumed missile and drone strikes this month after a nearly two-month lull.
Waves of attacks now come several times a week, the most intense of the war.
Russian administration: Zaporizhzhia nuclear plant cut from power grid
The Zaporizhzhia nuclear power plant was switched to standby, a Russia-installed local official in the Moscow-controlled part of the region said.
Vladimir Rogov said the plant was "completely" disconnected from the external power supply after Ukraine disconnected a power line it controls.
Ukraine's nuclear agency Energoatom accused Russia of carrying out an attack that caused the power cut.
The agency said the shelling caused the seventh instance of the plant entering "blackout mode" since Moscow's troops took control in March 2022.
Anatoliy Kurtev, Zaporizhzhia city council's secretary in Ukraine, said that work was ongoing since early Monday to restore power to the city.
On several occasions, the Zaporizhzhia power plant has been the center of intense fighting between Russian and Ukrainian fighters, causing concern from international nuclear experts who feared a potential accident at the facility.
Ukraine's Zaporizhzhia region is one of four areas of Ukraine illegally annexed by Russia last year.