Russia-Ukraine updates: US sanctions Russian military shipbuilder, diamond miner

British Prime Minister Boris Johnson on Thursday said consequences would be "very, very severe" if Vladimir Putin deploys chemical weapons.

"I think it would be catastrophic for him if he were to do that. And I think that he understands that," Johnson said.

He added that he thinks Biden was right in saying Putin's comments are a "clear sign" Russia is weighing the use of chemical weapons.

"I think [President] Joe Biden is right to warn ... because you know, when the Russians start doing this stuff about, 'oh, well … the factories in Ukraine producing American biological weaponry,' you know that is a prelude to a false flag operation and they could well do something, but I think it will make a profound and a disastrous mistake for Putin."

-ABC News' Christine Theodorou

President Joe Biden spoke to reporters Thursday, hours after a NATO emergency summit, saying that Russia's President Vladimir Putin "was banking on NATO being split," but NATO has never been more united than it is today.

"My early conversation with him in December and early January, it was clear to me he didn't think we could sustain this cohesion. NATO has never, never been more united than it is today. Putin is getting exactly the opposite of what he intended to have as a consequence of going into Ukraine," Biden said.

Biden has warned Russia may use chemical weapons in Ukraine and said that the U.S. and NATO would respond if they are used. Biden said the response would depend on the nature of the use of the weapons.

When asked whether this means they could cross the border into Ukraine, Biden said this is a decision they would make at the time.

The president said that he believes Russia should be removed from the G-20, but he raised the possibility that if removing Russia can’t be done because of "Indonesia and others" not in agreement, Ukraine should be able to attend future G-20 meetings.

Biden also spoke about the 100,000 Ukrainian refugees the U.S. will accept, with the caveat that they will be accepted "with a focus on reuniting families."

The United Nations General Assembly on Thursday voted to pass a resolution titled "Humanitarian consequences of the aggression against Ukraine," which explicitly names Russia as an aggressor party.

The resolution demands that Russia withdraw its military forces outside the internationally recognized borders of Ukraine.

It also condemns violations of humanitarian law and human rights abuses and seeks protections for civilians.

The resolution passed with 140 countries voting in favor, five voting against and 38 abstaining. The countries voting against the resolution were: Russia, Belarus, Syria, Eritrea and North Korea.

-ABC News' Zoha Qamar

In an address to the Group of 7 nations Thursday, Ukraine's President Volodymyr Zelenskyy called for a "full embargo on trade with Russia" and harsher restrictions on Russia's economy.

"Russian banks and, most importantly, the Central Bank of Russia, must get a complete blockade from the global financial system. War criminals should be left without money at all! And their frozen assets should turn, inter alia, into reparations for the reconstruction of Ukraine," Zelenskyy said.

Zelenskyy also warned of the risk Russia poses to Europe.

"It is better to give Ukraine the kind of weaponry support we really need now than to look for weapons for other countries later. We mean Georgia, Moldova, the Baltic States, Poland and Central Asia," he said.

-ABC News' Fidel Pavlenko