Russian President Vladimir Putin's "special military operation” into Ukraine began on Feb. 24, with troops crossing the border from Belarus and Russia. Moscow's forces have since been met with “stiff resistance” from Ukrainians, according to U.S. officials.
Russian forces retreated last week from the Kyiv suburbs, leaving behind a trail of destruction. After graphic images emerged of civilians lying dead in the streets of Bucha, U.S. and European officials accused Russian troops of committing war crimes.
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.
Mar 16, 2022, 11:09 AM EDT
House and Senate leadership to receive classified briefings
House and Senate leadership, along with ranking members of relevant committees, will receive a classified briefing on the war in Ukraine following Ukrainian President Volodymyr Zelenskyy's personal and emotional plea to Congress for more help.
Ukrainian President Volodymyr Zelenskyy delivers a virtual address to Congress by video at the Capitol in Washington, D.C., March 16, 2022.
Sarah Silbiger/Pool via AP
The House briefing will be at 2 p.m. Wednesday and the Senate will follow at 3:30 p.m.
-ABC News' Rachel Scott, Mariam Khan
Mar 16, 2022, 10:49 AM EDT
Jake Sullivan warns of consequences if Russia uses chemical or biological weapons
White House national security adviser Jake Sullivan spoke with his Russian counterpart, Nikolay Patrushev, on Wednesday “to reiterate the United States’ firm and clear opposition to Russia’s unprovoked and unjustified invasion of Ukraine,” National Security Council spokesperson Emily Horne said in a statement.
She said Sullivan told Patrushev that Russia should stop attacking Ukraine if it's serious about diplomacy and warned “about the consequences and implications of any possible Russian decision to use chemical or biological weapons in Ukraine.”
Horne said Sullivan “clearly laid out” that the U.S. will continue “imposing costs on Russia” as well as support Ukraine and defend NATO’s eastern flank.
This conversation marked the first high-level engagement between the U.S. and Russia since the Kremlin launched its war against Ukraine.
In a speech Wednesday, Russian President Vladimir Putin falsely claimed that Russia’s military tactics have been “completely justified” and that Russian troops are “doing everything possible” to avoid harming Ukrainian civilians.
Rescuers work next to an apartment building that was hit by shelling, as Russia's attack on Ukraine continues, in Kyiv, Ukraine, March 16, 2022.
Thomas Peter/Reuters
Rescuers work at a site of a burning warehouse after it was shelled, as Russia's attack on Ukraine continues, in Kharkiv, Ukraine, March 16, 2022.
Vitalii Hnidyi/Reuters
Putin sought to justify Russia’s invasion, claiming that all “diplomatic possibilities were exhausted” and Russia had “no choice” but to launch its operation. He claimed that the “appearance of Russian troops near Kyiv and other Ukrainian cities” is not connected “with a goal of occupying that country” and that it is about defusing a supposed threat to Russia.
-ABC News' Patrick Reevell
Mar 16, 2022, 9:38 AM EDT
Zelenskyy asks Congress to back no-fly zone over Ukraine
In a virtual address to members of Congress Wednesday, Ukrainian President Volodymyr Zelenskyy asked the U.S. to back a no-fly zone over the war-torn country.
If a no-fly zone is not possible, Zelenskyy asked for aircraft "to help Ukraine."
"Russia has turned the Ukrainian sky into a source of death for thousands" -- a "terror" Europe hasn't seen in 80 years, Zelenskyy said.
Ukrainian President Volodymyr Zelenskyy addresses members of Congress from Kyiv, March 16, 2022, in Washington, D.C.
ABC News
Members of Congress gather to hear a virtual address by Ukrainian President Volodymyr Zelenskyy, March 16, 2022, in Washington, D.C.
ABC News
In an emotional appeal, Zelenskyy asked members of Congress to put themselves in the shoes of Ukrainians by remembering Pearl Harbor and the Sept. 11 attacks.
Zelenskyy expressed his gratitude for U.S. involvement, but called on Congress to do more.
Members of Congress watch as President Volodymyr Zelensky of Ukraine delivers a virtual address to Congress in the U.S. Capitol Visitors Center Congressional Auditorium, March 16, 2022, in Washington, D.C. Zelenskyy addressed Congress as Ukraine continues to defend itself from an ongoing Russian invasion.
Sarahbeth Maney/Pool via Getty Images
"New packages of sanctions are needed constantly … we propose that the United States sanction all politicians in the Russian Federation who remain in their offices and do not cut ties with those who are responsible for the aggression against Ukraine," he said.
"Members of Congress, please take the lead. If you have companies in your districts who finance the Russian military machine... you should put pressure," he said.
"The destiny of our country is being decided," he said. "Russia has attacked not just us… it went on a brutal offensive against our values, basic human values."
Zelenskyy received a standing ovation before and after his remarks.
But White House press secretary Jen Psaki said Tuesday that a no-fly zone "is escalatory and could prompt a war with Russia."
"Providing the planes, our military did an assessment that’s based not just on the risk but whether it would have a huge benefit to them," Psaki said. "They assessed it would not because they have their own squadron of planes and because the type of military assistance that is working to fight this war effectively is the type of assistance we're already providing."