President Joe Biden on Wednesday called Russian President Vladimir Putin a "war criminal" for the first time.

In a brief exchange with reporters, Biden was asked whether he believes Putin is a war criminal amid the crisis in Ukraine. Biden initially said no and then asked the reporter to repeat the question.

"I think he is a war criminal," Biden said in response.

The Biden administration has been deliberating the potential ramifications of war crimes investigations of Russia and what role the U.S. should play in those international efforts, NBC News has reported.

Among the questions is whether indicting Putin could close the door on diplomacy or prompt him to resort to more drastic measures.

In a video uploaded to Telegram on Wednesday, Ukrainian President Volodymyr Zelenskyy appears to speak with Ivan Fyodorov, the Melitopol mayor who was kidnapped by Russian soldiers nearly a week ago — suggesting the mayor has been released.

In the video, Zelenskyy appears to congratulate Fyodorov on his rescue and reassures him that Ukraine does not leave its people behind. In what seemed to be a tongue-in-cheek exchange, the mayor then says he needs a day or two before he returns to work. In response, Zelenskyy says he cannot promise two days but encourages the mayor to rest.

The video was posted by the deputy head of Zelenskyy's office. The deputy head of the president's office, Kyrylo Tymoshenko, said in a separate post that the rescue was a special operation.

Russian forces bombed a theater where hundreds of Ukrainian civilians were sheltering in the besieged port city of Mariupol on Wednesday, the country's foreign minister said in a tweet, calling the attack a "horrendous war crime."

"The building is now fully ruined. Russians could not have not known this was a civilian shelter," Ukrainian Foreign Minister Dmytro Kuleba tweeted, adding: "Save Mariupol! Stop Russian war criminals!"

It was not immediately clear how many civilians were killed. NBC News has not independently verified the attack. Russia has denied targeting civilians.

In a message on Telegram, Mariupol's city council condemned what it described as Russia's "horrific and inhumane act."

"Today, racist troops purposefully and cynically destroyed the Drama Theater in the heart of Mariupol," the council said, according to an NBC News translation. "The plane dropped a bomb on a building where hundreds of peaceful Mariupol residents were hiding."

Russian media sources, citing the country's Defense Ministry, claimed that "Ukrainian nationalists" blew up the theater, without providing evidence.

President Joe Biden announced Wednesday that he is authorizing $800 million in U.S. assistance to Ukraine, bringing the total of announced new security aid for the country to $1 billion just this week. 

"These are direct transfers of equipment from our Department of Defense to the Ukrainian military, to help them as they fight against this invasion," Biden said in remarks from the White House, flanked by top officials, including Secretary of State Antony Blinken and Joint Chiefs of Staff Chairman Mark Milley. 

Biden said the new package includes: 

• 800 anti-aircraft systems 
• Additional longer-range anti-aircraft systems and their munitions
• 9,000 anti-armor systems, which he said are "portable high-accuracy shoulder mounted missiles"
• 7,000 small arms, including machine guns, shotguns and grenade launchers 
• 20 million rounds of ammunition, artillery and mortars for small arms
• Drones 

"The United States and our allies and partners are fully committed to surge the weapons of assistance to the Ukrainians, and more will be coming as we source additional stocks of equipment," Biden said, adding bluntly: "Now, I want to be honest. This could be a long and difficult battle. But the American people will be steadfast in our support of the people of Ukraine in the face of Putin's immoral, unethical attacks on civilian populations."

Biden said the U.S. has provided $300 million in humanitarian assistance in the last few weeks to people in Ukraine and in neighboring countries where Ukrainians are finding refuge. This assistance has included food, medicine and basic supplies, he said. 

When the invasion began in late February, Biden said, the U.S. rushed $350 million in additional aid, including anti-tank weapons, transport helicopters, armed patrol boats, unmanned drones, secure communications equipment, tactical gear, other high-mobility vehicles and radar systems that help track incoming artillery. He also said the administration started sending assistance to Ukraine a year ago. "We took the threat of Putin invading very seriously. We acted on it. We sent Ukraine more security systems last year — $650 million in weapons, including anti-air and anti-armor equipment — before the invasion, more than we had ever provided before."

A group of Republican senators Wednesday praised Zelenskyy's address to Congress and demanded that the Biden administration send more weapons to Ukraine like the Soviet-era MiG fighter jets. 

"What we need to do is change our approach," Sen. Rob Portman, R-Ohio, said at a news conference. 

Portman said the U.S. needs to be more creative in helping Ukraine — and quickly — such as by providing anti-aircraft systems, drones and everything else it can to protect the country as it faces constant bombardment by Russia. 

"If it shoots, we should ship it," Sen. Ben Sasse, R-Neb., said, including drones and Javelin and Stinger missiles. 

Sen. Joni Ernst, R-Iowa, said she will be leading a congressional delegation trip of nine colleagues to Poland. She didn't say when the trip will take place. 

"We are going to see firsthand the humanitarian crisis and the devastation that this war has created. And we will ensure that Ukraine and our NATO partners are getting all of the support that they need," she said. 

The International Court of Justice, the world's highest court, ordered Russia on Wednesday to immediately halt military operations in Ukraine, a preliminary decision in response to allegations of genocide brought by Ukraine. 

"The Russian Federation shall immediately suspend the military operations that it commenced on Feb 24, 2022 on the territory of Ukraine," the 13-2 ruling read. 

A second order, which also received a 13-2 vote, said Russia "shall ensure that any military or irregular armed units which may be directed or supported by it, as well as any organizations and persons which may be subject to its control or direction, take no steps in furtherance of the military operations."

The two votes against the measures were those of the court's vice president, Kirill Gevorgian of Russia, and Chinese jurist Xue Hanqin. 

The U.N. body also unanimously voted that both parties should "refrain from any action which might aggravate or extend the dispute before the court or make it more difficult to resolve."

Russian representatives did not attend hearings in the case March 7 and 8. 

MEDYKA, Poland  —  Parents, spouses, children, grandchildren, sweethearts, friends, careers and homes: That’s just a short list of all that was left behind by so many fleeing war in their homeland.

The immensity of what remains in Ukraine contrasts starkly with the meager possessions these sudden refugees were able to bring with them. All that they own now is crammed into shopping bags and wheeled suitcases that squeak and rattle as they cross into this small red-brick village surrounded by fields.

With shock, grief and relief hanging in the bright, cold air, Alexander Federov greets the new arrivals in Poland with a broad smile and some hearty Ukrainian warmth: “Vse bude dobre” — “Everything will be fine.”

About 3 million Ukrainians have fled since Russia invaded their country — the majority to neighboring Poland — in the fastest-growing refugee crisis in Europe since World War II. Thousands of them have crossed through Medyka.

Read the full story here.

The website of a Ukrainian news outlet was hacked Wednesday and used to push a fake video in which someone who appears to be Zelenskyy tells citizens to surrender to Russia, one of the most high-profile uses of "deepfake" technology to date.

The live TV broadcast from the media outlet, Ukraine 24, also showed a chyron that repeated what the fake Zelenskyy video said.

Disinformation experts have long warned that deepfakes, computer-generated videos of a real person saying or doing things they didn't actually say or do, could be used for malicious political purposes, and Ukrainian government officials have warned for weeks that Russia may try to convince people of false news of surrender.

The simulation was of low quality, with the fake Zelenskyy's mouth moving unnaturally, his head appearing somewhat detached from his body.

Last week, Ukraine provincial government websites were hacked to make similar claims, leading national government officials to rush to debunk it. Channel 24's website was down as of midday Wednesday, but its Telegram channel warned about the hack and said that the message of surrender was fake.

Russian President Vladimir Putin claimed without evidence Wednesday that Ukraine has its own nuclear weapons and biological weapons programs. 

"Kyiv government announced their own nuclear weapons and the means to transport it. It was a real threat. In the near future, with foreign technical help, the Nazi regime in Kyiv could get hold of weapons of mass destruction," Putin said in remarks on Russia-24, a state-owned Russian news channel. "And Russia would, of course, be the target."

Putin also claimed that Ukraine has laboratories where it conducts experiments with "coronavirus, anthrax, cholera, African swine fever and other lethal diseases," adding: "They are trying to cover the traces of these programs. In essence, they were creating biological weapons in close proximity to Russian borders." He also accused Ukraine of planning to attack Donbas and Crimea in an "ethnic cleansing."

Putin suggested he was forced to authorize the invasion because Russia was "left with no choice for peaceful resolution of problems that we are not to blame for."

U.S. officials have been warning that Russia could implement a false flag operation in which its military would launch a chemical or biological weapons attack in Ukraine.