Russian President Vladimir Putin's "special military operation" into neighboring Ukraine began on Feb. 24, with Russian forces invading from Belarus, to the north, and Russia, to the east. Ukrainian troops have offered "stiff resistance," according to U.S. officials.
The Russian military has since launched a full-scale ground offensive in eastern Ukraine's disputed Donbas region, capturing the strategic port city of Mariupol and securing a coastal corridor to the Moscow-annexed Crimean Peninsula.
A look at the two leaders at the center of the war in Ukraine and how they both rose to power, the difference in their leadership and what led to this moment in history.
Here's how the news is developing. All times Eastern.
Apr 12, 2022, 9:28 PM EDT
White House could announce up to $750M in new Ukrainian military aid, official says
The Biden administration could announce as early as Wednesday upward of $750 million in additional military assistance to Ukraine, a U.S. official told ABC News.
The new assistance could possibly include a range of military hardware -- including howitzers, artillery and Humvees -- though the full package still needs to be finalized, the official said.
-ABC News' Luis Martinez
Correction: Mi-17 helicopters are not being considered as part of the package, as previously reported.
Apr 12, 2022, 6:48 PM EDT
Biden uses 'genocide' for first time regarding Ukraine
President Joe Biden used the word "genocide" for the first time to describe Russia's actions in Ukraine during remarks on Tuesday.
"Your family budget, your ability to fill up your tank -- none of it should on hinge on whether a dictator declares war and commits genocide half a world away," Biden said in Menlo, Iowa, during remarks primarily about the U.S. economy.
Biden was asked by reporters on April 4 if he thought the atrocities in Bucha were a genocide, as Ukrainian President Volodymyr Zelenskyy had claimed. "No, I think it is a war crime," Biden responded then.
That same day, Biden's national security adviser, Jake Sullivan, said the administration had not yet seen the "systematic deprivation of life" necessary to meet the definition of genocide.
Police officers work on identifying bodies of civilians, before sending them to the morgue, in Bucha, northwest of Kyiv, Ukraine, on April 6, 2022.
Rodrigo Abd/AP
Biden confirmed his word choice to the White House pool Tuesday evening before boarding Air Force One, saying that since last week the "evidence is mounting."
"Yes, I called it genocide," Biden said. "Because it has become clearer and clearer that Putin is just trying to wipe out the idea of even being able to be a Ukrainian."
He then qualified that the determination of genocide is officially up to legal experts, but that "it sure seems that way to me."
-ABC News' Sarah Kolinovsky
Apr 12, 2022, 5:34 PM EDT
US State Department condemns arrest of Russian opposition activist
The U.S. State Department is condemning the arrest in Russia of Vladimir Kara-Murza, a Russian opposition activist and critic of the Kremlin's invasion of Ukraine.
State Department spokesperson Ned Price said Kara-Murza's arrest on Monday is another example of a Russian government "that is more aggressive beyond its borders and more oppressive within its borders."
Vladimir Kara-Murza, Russian opposition activist, arrives to lay flowers near the place where Russian opposition leader Boris Nemtsov was gunned down, in Moscow, Feb. 27, 2021.
Alexander Zemlianichenko/AP, FILE
He condemned Kara-Murza's arrest, noting that the activist has previously been arrested by Russian authorities and that he has survived two poisoning incidents.
"The Russian people -- and this is the key point -- like people everywhere, have the right to speak freely, to form peaceful associations, to exercise their freedom of expression and to have their voices heard through free and fair elections," Price said.
Kara-Murza, a Washington Post columnist who has testified before Congress, survived poisoning incidents in 2015 and in 2017. At the time of his second poisoning, Kara-Murza's wife, Evgenia Kara-Murza, gave an exclusive interview to ABC News in which she pleaded for then-President Donald Trump to support her husband and warned that Putin "cannot be dealt with on friendly terms."
Following her husband's arrest this week, Evgenia Kara-Murza posted a message on Twitter calling attention to her husband's arrest.
"Twice have the Russian authorities tried to kill my husband for advocating for sanctions against thieves and murderers, and now they want to throw him in prison for calling their bloody war a WAR. I demand my husband's immediate release!" Evgenia Kara-Murza, who lives in the Washington, D.C., area, tweeted.
-ABC News' Conor Finnegan
Apr 12, 2022, 4:04 PM EDT
Pro-Russian oligarch captured in Ukraine: Zelenskyy
Viktor Medvedchuk, a pro-Russian oligarch and personal friend of Vladimir Putin, has been captured in Ukraine, Ukrainian President Volodymyr Zelenskyy said.
Zelenskyy posted a photo on his official Telegram account of the captured Medvedchuk in handcuffs and wearing military fatigues.
The photo was accompanied by a caption praising the Security Service of Ukraine's "special operation" that led to Medvedchuk's capture. "Well done! Details later. Glory to Ukraine," the caption reads.
Pro-Russian Ukrainian politician Viktor Medvedchuk in handcuffs is seen after been detained by security forces in unknown location in Ukraine, in this handout picture released April 12, 2022.
Press Service of State Security Service of Ukraine via Reuters
Medvedchuk is a pro-Russian Ukrainian politician and leader of Ukraine's Opposition Platform.
In May 2021, Ukraine indicted Medvedchuk on charges of treason and attempting to steal natural resources from Russia-annexed Crimea. He was initially placed under house arrest in Ukraine but escaped just days after the Russian invasion began on Feb. 24.
Medvedchuk's detention was also confirmed by Ukraine's Security Service on their official Facebook page. The agency said Medvedchuk was wearing a uniform from the Ukrainian armed forces to disguise himself.
Medvedchuk is a business oligarch in Ukraine with very close ties to Putin. The Ukrainian National News Agency reported that Putin is the godfather of one of Medvedchuk's daughters.
