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 26, 2022, 9:46 AM EDT
Biden, Poland's president hold bilateral meeting
President Joe Biden arrived at the Polish presidential palace Saturday for a bilateral meeting with Polish President Andrjez Duda, as the Russian invasion of Ukraine continues.
Biden and Duda shook hands and stood shoulder to shoulder as both countries' national anthems played.
U.S. President Joe Biden, left, and Polish President Andrzej Duda shake hands during a military welcome ceremony at the Presidential Palace in Warsaw, Poland, on March 26, 2022.
Czarek Sokolowski/AP
Biden was met by three branches of the Polish military, as the two leaders reviewed the troops. They then headed inside for the meeting.
Polish President Andrzej Duda and U.S. President Joe Biden confer during their meeting at the Presidential Palace in Warsaw, Poland, March 26, 2022.
Marcin Obara/EPA va Shutterstock
Biden was joined by a delegation of seven U.S. officials, including Secretary of State Antony Blinken and Secretary of Defense Lloyd Austin, who participated in the meeting, according to the White House.
The Polish delegation consisted of six officials, including the ministers of foreign affairs and national defense, according to the White House.
-ABC News' Molly Nagle
Mar 26, 2022, 9:40 AM EDT
Biden drops by meeting between US and Ukrainian officials
President Joe Biden dropped by a meeting between U.S. Secretary of State Antony Blinken and Secretary of Defense Lloyd Austin and their Ukrainian counterparts Saturday morning.
The meeting between the secretaries lasted for an hour and 46 minutes, according to the State Department.
President Joe Biden participates in a meeting with Ukrainian Foreign Minister Dmytro Kuleba, second from left, and Ukrainian Defense Minister Oleksii Reznikov, left, Saturday, March 26, 2022, in Warsaw. Defense Secretary Lloyd Austin, right, and Secretary of State Antony Blinken, third from right, look on.
Evan Vucci/AP
The two secretaries pledged continued U.S. economic, military and humanitarian aid to Ukraine and provided the Ukrainians updates after Thursday's NATO, EU and G-7 summits.
"The Secretaries and Ministers discussed outcomes of the March 24 extraordinary NATO Summit in Brussels, and the United States’ unwavering commitment to Ukraine’s sovereignty and territorial integrity in the face of the Russian Federation’s increasingly brutal assault on Ukrainian cities and civilian population," said Ned Price, a spokesperson for the Department of State, in a statement.
In a statement from the White House, Biden reaffirmed the U.S.'s commitment to Ukraine, saying the officials discussed further efforts to help Ukraine defend its territory.
"The President updated the Ministers on U.S. efforts to rally the world in support of Ukraine’s fight against Russian aggression, including through the President’s meetings this week in Belgium, and the significant military and humanitarian assistance the United States is providing to Ukraine," the White House said in a statement.
The White House added: "They also discussed the United States’ ongoing actions to hold President Putin accountable for Russia’s brutal aggression, in coordination with our allies and partners, including through the new sanctions actions announced by the President in Brussels on March 24.
-ABC News' Conor Finnegan and Sarah Kolinovsky
Mar 26, 2022, 9:24 AM EDT
Unexploded missile near nuclear site in Kharkiv cause for concern, IAEA says
There is an unexploded missile in the immediate vicinity of the nuclear research facility in Kharkiv, Ukraine's regulatory authority told the International Atomic Energy Agency.
The IAEA said it is continuing to monitor the situation.
"The regulator confirmed reports of an unexploded rocket of the multiple launch rocket system 9K58 Smerch 'detected in the immediate vicinity' of a nuclear research facility that has previously been damaged by shelling," the IAEA said in a statement.
It added: "the regulator said 'constant shelling' of the area meant that no measures had yet been taken to dispose of the rocket."
The facility is used for research and development and radioisotope production for medical and industrial applications. The site's nuclear material cannot sustain a fission chain reaction and the radioactive inventory is low, according to the IAEA.
Eight of Ukraine's 15 operational reactors, at four sites, are continuing to operate, including two at the Zaporizhzhya power plant. The other reactors are shut down for regular maintenance, the IAEA said.
-ABC News' Guy Davies
Mar 26, 2022, 8:38 AM EDT
136 children have been killed, 199 injured, Ukraine officials say
Ukraine's prosecutor's office said that 136 children have been killed in the war and 199 have been injured, as of Saturday morning local time.
The grim update comes on Day 31 of Russia's invasion of Ukraine.
