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 25, 2022, 11:12 AM EDT
Biden thanks troops in Poland
In Jasionka, Poland, on Friday, President Joe Biden and Secretary of Defense Lloyd Austin visited American troops, thanking them for working alongside Polish allies.
Biden and Austin first greeted members of the 82nd Airborne Division in a makeshift barbershop.
President Joe Biden visits with members of the 82nd Airborne Division at the G2A Arena, Friday, March 25, 2022, in Jasionka, Poland.
Evan Vucci/AP
President Joe Biden meets with members of the 82nd Airborne Division, who are contributing alongside Polish allies to deterrence on the alliance's eastern flank, in Rzeszow, Poland, around 100 kilometres (62 miles) from the border with Ukraine, on March 25, 2022.
Brendan Smialowski/AFP via Getty Images
Biden and Austin then stopped by a mess hall and ended up staying for a slice of pizza.
President Joe Biden takes a selfie with members of the 82nd Airborne Division in the city of Rzeszow in southeastern Poland, around 100 kilometres (62 miles) from the border with Ukraine, on March 25, 2022.
Brendan Smialowski/AFP via Getty Images
President Joe Biden visits with members of the 82nd Airborne Division at the G2A Arena, March 25, 2022, in Jasionka, Poland.
Evan Vucci/AP
President Joe Biden eats a pizza slice as he meets with members of the 82nd Airborne Division in the city of Rzeszow in southeastern Poland, around 100 kilometres (62 miles) from the border with Ukraine, on March 25, 2022.
Brendan Smialowski/AFP via Getty Images
Biden also shared a story about searching for his son, Beau, in a mess hall in Baghdad, only to find him using his mother's maiden name -- Hunter -- on his fatigues.
"I said, 'Beau, what the hell’s going on?' His name was Beau Biden, and he was a colonel, I mean, a major, excuse me," Biden said.
"And I said, 'What happened?' And he said, 'Dad, with the name Biden, everybody thinks something’s going on. So I’m Hunter.' That was his mother’s maiden name," Biden said.
-ABC News' Molly Nagle
Mar 25, 2022, 10:29 AM EDT
Ukrainian troops have retaken towns, UK intelligence says
Ukrainian troops have been able to retake towns and defensive positions up to 35 kilometers (about 22 miles) east of Kyiv due to counter-attacks and Russian forces falling back on overextended supply lines, the U.K. Ministry of Defense said Friday in an intelligence update on the situation.
Pro-Russian troops are seen atop of an armored vehicle with the symbol "Z" painted on its side in the besieged southern port city of Mariupol, Ukraine on March 24, 2022.
Alexander Ermochenko/Reuters
Ukrainian troops are likely to continue to attempt to push Russian forces back along the northwestern axis from the Ukrainian capital toward Antonov Airport in Hostomel, a suburb of Kyiv, according to the U.K. Ministry of Defense.
In southern Ukraine, Russian forces are still attempting to circumvent the densely populated city of Mykolaiv as they look to drive west toward Odesa, with their progress being slowed by logistic issues and Ukrainian resistance, the U.K. Ministry of Defense said.
Mar 25, 2022, 10:25 AM EDT
Biden arrives in Poland
U.S. President Joe Biden arrived at Poland's Rzeszow-Jasionka Airport Friday afternoon, where he will get a firsthand look at the international efforts to help some of the millions of people fleeing Ukraine.
President Joe Biden arrives at Rzeszow-Jasionka Airport, March 25, 2022, in Jasionka, Poland.
Evan Vucci/AP
Biden was greeted on the tarmac by four U.S. commanding generals. While in Rzeszow on Friday, Biden will receive a briefing on the humanitarian situation and meet with humanitarian aid groups as well as service members of the U.S. Army's 82nd Airborne Division.
He will later travel to Warsaw, where he will meet with Polish President Andrzej Duda as well as refugees from Ukraine on Saturday.
Mar 25, 2022, 10:07 AM EDT
US says Russia's attacks on Ukraine could put NATO at risk
U.S. President Joe Biden's support of NATO battlegroups on the eastern flank stems from the belief that Russia's attacks in Ukraine have the capacity to put the alliance's territories at risk, according to White House national security adviser Jake Sullivan.
"We do believe Russian aggression in Ukraine shows a willingness by the Russians to disregard international borders and to disregard the basic rules of the road of the international community that have been built in sustained over the course of seven decades," Sullivan told reporters aboard Air Force One on Friday.
"It is important in this moment to send a clear message to Russia that the United States and NATO will defend every inch of NATO territory and to deter any thinking that Putin might have about further Russian aggression into NATO."
A woman walks past flames and smoke rising from a fire following artillery shelling on the 30th day of the invasion of Ukraine by Russian forces in the northeastern Ukrainian city of Kharkiv on March 25, 2022.
Aris Messinis/AFP via Getty Images
Sullivan noted that Belarus' willingness to station Russian troops on its soil, in particular, has a "significant impact particularly on our NATO allies in the Baltics and Poland."
Sullivan said Biden has made clear that any diplomatic agreement reached is one that Ukraine will have to determine for itself, meaning Washington is not going to push or pressure Kyiv into any outcome.
Currently, Washington's priority is to ensure Ukraine has the capabilities to defend itself as Russian forces continue pushing forward, Sullivan told reporters.
