This has been CNBC's live blog covering updates on the war in Ukraine. [Follow the latest updates here.]
Ukraine President Volodymyr Zelenskyy has pledged to pursue allegations of war crimes against Russian forces in occupied regions of the country.
Zelenskyy said that more than 300 people were killed and tortured in the town of Bucha, a suburb near the capital of Kyiv, reflecting on what he described as a "hard and emotional" day after visiting the area. Russia has denied the allegations, without providing evidence.
Zelenskyy on Tuesday addressed an emergency meeting of the United Nations Security Council and called for a Nuremberg-style tribunal to investigate and prosecute war crimes in Ukraine. He said the Russian military "must be brought to justice immediately" for their crimes in Ukraine.
Appealing to Russians in their own language, U.K. Prime Minister Boris Johnson said in a video address: "Your president stands accused of committing war crimes. But I cannot believe he's acting in your name."
British Prime Minister Boris Johnson called on Russians to "find the truth" and "share it."
"Your president stands accused of committing war crimes. But I cannot believe he's acting in your name," Johnson said in a video directly addressing the Russian people.
Speaking in both Russian and English, he said: "The atrocities committed by Russian troops in Bucha, Irpin and elsewhere in Ukraine have horrified the world."
He went on to outline the alleged atrocities of Russian troops: civilians massacred, women raped, bodies burned and "dumped in mass graves, or just left lying in the street."
Ukrainian officials say that more than 300 civilians were tortured and killed by Russian troops in the town of Bucha outside Kyiv, discoveries made only after Moscow pulled out of those areas.
Graphic media images also revealed corpses of civilians in the streets — some with their hands and legs tied up — while satellite images captured mass graves.
Russia has been waging information warfare alongside its military operations.
The Russian people have been "fed a steady diet of propaganda" by Russian-state media, according to NBC News' Ken Dilanian. The Kremlin has labeled the unprovoked and unwarranted war in Ukraine a "special military operation."
"The reports are so shocking, so sickening, it's no wonder your government is seeking to hide them from you," Johnson said.
"But don't just take my word for it," he added, calling on them to access independent information via VPN connection. "And when you find the truth, share it."
— Charmaine Jacob, Joanna Tan
Intel has suspended all business operations in Russia, the U.S. chipmaker announced.
"Intel continues to join the global community in condemning Russia's war against Ukraine and calling for a swift return to peace. Effective immediately, we have suspended all business operations in Russia," the company said in a statement.
This follows the company's move a month ago to suspend all shipments to Russia and Belarus.
"We are working to support all of our employees through this difficult situation, including our 1,200 employees in Russia," it said.
Intel joins a list of growing software companies that have stopped operations or shipments to Russia, including Oracle, SAP, and IBM.
— Chelsea Ong
More Russian atrocities like those seen in the Kyiv suburb of Bucha may emerge, says Jeffrey Edmonds, a senior research scientist at CNA, a research organization.
"When you look at such things in history, they have happened at various times, when units are really depleted and leadership has demonized the people they're fighting," Edmonds told CNBC's "Squawk Box Asia."
Ukrainian President Volodymyr Zelenskyy has accused Russian troops of killing and torturing more than 300 people in the city of Bucha, as Western leaders condemned images of slain Ukrainian civilians in a town previously occupied by Russian forces.
Russia has denied those allegations, but journalists and Ukrainians living in the city have confirmed the civilian killings. Satellite images from space company Maxar Technologies captured also mass graves.
"Unfortunately, given how beat they are and the fact that Putin has created the conditions under which this would happen, I think we might see more," he added.
— Chelsea Ong
President Joe Biden authorized the immediate release Tuesday of an additional $100 million worth of Javelin anti-tank missiles and training for Ukraine, according to statements from the Pentagon and the State Department.
The announcements late Tuesday night were the first concrete evidence that the United States plans to respond to the growing evidence of alleged Russian war crimes in Ukraine in part by increasing the lethality of Kyiv's fighting force.
"The world has been shocked and appalled by the atrocities committed by Russia's forces in Bucha and across Ukraine," Secretary of State Antony Blinken said in a statement on the last-minute additional funding.
The formerly occupied Ukrainian village of Bucha was the scene of dozens of alleged war crimes by Russian troops, which were only discovered after the Kremlin ordered its soldiers to retreat.
The Javelin is a shoulder-fired, target-locking missile system that can destroy a tank on the move from a distance of more than a mile. As outnumbered Ukrainian forces fight to halt the progress of advancing infantry in Russian tanks, no weapon so far has been as effective or deadly as the U.S.-made Javelins.
— Christina Wilkie
Photos show total destruction in the small city of Borodyanka, located northwest of Kyiv, which was the scene of heavy clashes for weeks while the Russian military were there until about four days ago. Ukrainian forces have regained the control of the town.
— Getty Images
The United Nation's said an eight-truck convoy of humanitarian supplies reached Sievierodonetsk in eastern Ukraine's Luhansk region, where sustained fighting is "taking an enormous toll on civilians."
"The UN and humanitarian partners delivered ready-to-eat meals, canned goods, flour and essential relief items such as blankets, mattresses, solar-powered lamps, and other household items," UN Deputy Humanitarian Coordinator Markus said in a statement.
The supplies also included plastic sheeting and blankets for some 17,000 people, as well as electric generators for the local hospital. The UN estimates that 11.3 million Ukrainians have been uprooted by the war.
— Dawn Kopecki
Editor's Note: Graphic content. The following post contains an image of dead bodies.
Since the Kremlin's Feb. 24 invasion of Ukraine, the United Nations has confirmed 1,480 deaths and 2,195 injuries.
The international body adds that the death tolls in Ukraine are likely to be higher citing delayed reporting due to the armed conflict.
The UN says the war has created more than 4.2 million Ukrainian refugees, mostly the elderly, women and children.
— Amanda Macias
The highest U.S. military officer told lawmakers that the war in Ukraine could last for years, a revelation that comes as U.S. officials warn that Russia will intensify its campaign in Ukraine.
"I do think this is a very protracted conflict and I think it's at least measured in years, I don't know about a decade but at least years for sure," Chairman of the Joint Chiefs of Staff U.S. Army Gen. Mark Milley told the House Armed Services Committee.
"This is a very extended conflict that Russia has initiated and I think that NATO, the United States, Ukraine and all of the allies and partners that are supporting Ukraine are going to be involved in this for quite some time," he added.
Milley, who has served in the U.S. Army for four decades, described the war in Ukraine as the "greatest threat to the peace and security of Europe and perhaps the world."
"The Russian invasion of Ukraine is threatening to undermine the global peace and stability that my parents and generations of Americans fought so hard to defend," Milley added.
— Amanda Macias
The U.S. and its European allies are preparing to deliver another slew of sanctions on Russia following mounting evidence of war crimes in Ukraine, three people familiar with the matter tell NBC News.
The additional sanctions are expected to ban all new investments in Russia and state-owned enterprises.
The fresh sanctions package, taken in lockstep with European Union allies and Group of 7 members, will also designate Kremlin officials and their family members.
The sweeping measures come on the heels of global outrage over mounting evidence of Russian war crimes in Ukraine.
— Amanda Macias
Russian energy giant Gazprom said it has recalled its representatives from the management of Gazprom Germania and companies under its control.
Economy Minister Robert Habeck said on Monday that Gazprom Germania, an energy trading, storage and transmission business ditched by Gazprom on Friday, would be transferred to Germany's regulator to ensure energy security.
Gazprom also said that Gazprom Germania as well as Gazprom Marketing & Trading should stop using Gazprom's trademarks.
— Reuters
The United Nations official who oversees the humanitarian efforts in Ukraine said that the coastal city of Mariupol has become "the center of hell."
"For more than five weeks, the people of Mariupol have been caught up in the fighting and it is well documented that really Mariupol is the center of hell," UN humanitarian aid chief Martin Griffiths told the UN Security Council.
UN officials have warned that people living in Mariupol, a strategic city on the Sea of Azov, have lacked electricity, water, food and heat since nearly the start of the war.
More than a quarter of Ukraine's population has fled since Russia invaded Ukraine on Feb. 24, Griffiths said.
"The current figures on displacement tell us that more than 11.3 million people have now been forced to flee their homes and of that 4.2 million are now refugees," he said.
— Amanda Macias
Ukrainian President Volodymyr Zelenskyy called for a Nuremberg-style tribunal to investigate and prosecute Russian war crimes.
"The Russian military and those who gave them orders must be brought to justice immediately for war crimes in Ukraine," Zelenskyy said in a nearly 20-minute speech before the United Nations Security Council.
"Anyone who has given criminal orders and carried out them by killing our people will be brought before the tribunal which should be similar to the Nuremberg tribunals," he added.
Zelenskyy appeared before the international forum after Ukraine alleged that Russian troops tortured and killed hundreds of civilians in Bucha, near the capital of Kyiv.
"The massacre in our city of Bucha is only one, unfortunately, only one of many examples of what the occupiers have been doing on our land for the past 41 days," Zelenskyy said, adding that "the world has yet to see" what Russia has done elsewhere in Ukraine.
— Amanda Macias
U.S. Ambassador to the United Nations Linda Thomas-Greenfield said Tuesday that Russia must be suspended from the UN Human Rights Council in light of the new evidence of war crimes committed by Russian troops invading Ukraine.
"Given the growing mountain of evidence, Russia should not have a position of authority in a body whose purpose is to promote respect for human rights," Thomas-Greenfield argued during a Security Council meeting in New York.
"Not only is it the height of hypocrisy -- it is dangerous. Russia is using its membership on the Human Rights Council as a platform for propaganda to suggest Russia has a legitimate concern for human rights," she said.
In order to suspend Russia from the council it requires a majority of the members of the full UN General Assembly to approve the suspension. Thomas-Greenfield has said she will seek to hold that vote as early as this Thursday.
The Human Rights Council has a complicated history, and several of the 47 current member states have been accused of serious human rights abuses, including China, Venezuela and Russia.
— Christina Wilkie
Secretary of State Antony Blinken said the U.S. and its allies believe that the reports of Russian war crimes in Ukraine are "more than credible."
"What we've seen in Bucha is not the random act of a rogue unit. It's a deliberate campaign to kill, to torture, to rape, to commit atrocities. The reports are more than credible. The evidence is there for the world to see," Blinken told reporters on the tarmac at Joint Base Andrews in Maryland.
"We said before the aggression that we anticipated that if it went forward, there would be atrocities committed information that we've seen going into the aggression suggested that this will be part of the Russian campaign," Blinken said before boarding a flight to Belgium.
The State Department is taking the lead on behalf of the U.S. on helping with the UN's investigation into possible war crimes.
Blinken is on his way to Brussels for another urgent meeting of NATO foreign ministers. While in Brussels, he will also meet with ministers from the Group of Seven industrialized nations to consult on the response to reports of atrocities and war crimes allegedly carried out by Russian troops in Ukraine.
— Amanda Macias
Ukrainian President Volodymyr Zelenskyy will address the United Nations Security Council following global outrage over potential Russian war crimes in Bucha.
Zelenskyy said Monday officials discovered at least 300 civilians that were tortured and killed in Bucha by Russian troops. The bodies were discovered after Moscow withdrew its troops from the suburb near Ukraine's capital. The Ukrainian leader described the aftermath in Bucha as a "genocide."
Over the weekend, horrific images emerged of bodies scattered across the streets, some with their hands tied and gunshot wounds to the back of the head.
Zelenskyy's remarks to the international forum come ahead of a U.S.-led proposal to suspend Russia from the UN's Human Rights Council.
U.S. Ambassador Linda Thomas-Greenfield is set to introduce the proposal to the UN Security Council later today and to the General Assembly later this week.
— Amanda Macias
NATO Secretary-General Jens Stoltenberg said the alliance is working with the UN's International Criminal Court on investigating Russian war crimes in Ukraine.
Stoltenberg, who briefed reporters from NATO's headquarters ahead of tomorrow's foreign minister's meeting, said the alliance had mounting evidence of war crimes committed in Bucha as well as other cities in Ukraine.
"NATO allies are providing support to the UN International Criminal Court to collect evidence, to preserve evidence, to collect relevant information and to enable them to conduct investigations and to have a legal process to make sure that all those responsible for these atrocities are held accountable," Stoltenberg said.
"Targeting and murdering civilians is a war crime. All the facts must be established and all those responsible for these atrocities must be brought to justice," he said.
Stoltenberg also said that Ukrainian Foreign Minister Dmytro Kuleba will join the NATO ministerial this week.
— Amanda Macias
Kyiv Mayor Vitali Klitschko has accused Russia of committing genocide against Ukrainians, citing atrocities in Bucha, Irpin, Hostomel and other suburbs of the capital city.
"Russia, by brutally destroying Ukraine and peaceful Ukrainians, is a threat to the entire civilized world today. And the world must be aware of this," Klitschko said via Telegram, according to a translation.
"Stop not with sympathy and statements, but with real and decisive steps. Strict sanctions against the aggressor, military assistance to Ukraine," he added.
Russia has denied allegations of killing civilians.
— Sam Meredith
Russian forces have hit a tank with nitric acid in the eastern Ukrainian city of Rubizhne, according to Ukrainian officials, prompting toxic smoke to cover the area.
"Nitric acid is very dangerous if inhaled, swallowed or if it is in contact with skin," Ukraine's parliament said via Twitter. "The consequences of this incident are similar to usage of chemical or biological weapons!"
CNBC has not been able to independently verify this report.
Separately, Serhii Haidai, head of the Luhansk Regional State Administration, said authorities did not know how much nitrogen was in the tanks that were blown up.
"We clearly understand that there was nitric acid. This substance is quite toxic, so you need to watch the direction of the wind, use protective masks, or it is best to wait in the shelter until the first rain," Haidai said, according to a translation.
— Sam Meredith
The European Commission, the EU's executive arm, is expected to propose a ban on Russian coal as part of a new wave of sanctions targeting the Kremlin, two EU officials told CNBC on Tuesday.
The officials did not wish to be named due to the sensitivity of the talks.
Read the full story here.
— Sam Meredith
Here's a summary of the European countries that are expelling Russian diplomats over the Kremlin's war with Ukraine.
In some instances, Russia has said it will retaliate against the expulsions.
— Sam Meredith