The war is now in its fourth week. Overnight, Ukrainian President Volodymyr Zelenskyy accused the Kremlin of deliberately creating "a humanitarian catastrophe,'' but also appealed for Russian President Vladimir Putin to meet him for direct talks.
The U.N. migration agency says the fighting has displaced nearly 6.5 million people inside Ukraine, on top of the 3.2 million refugees who have already fled the country. Ukraine says thousands have been killed.
Here are some key things to know about the conflict:
WHAT IS HAPPENING ON THE GROUND?
In city after city around Ukraine, hospitals, schools and buildings where people sought safety have been attacked.
In Mariupol, Ukrainian troops were losing control of the key Azovstal steel plant, now damaged and heavily contested, according to comments from an adviser to Ukraine's interior minister.
"Now there is a fight for Azovstal," Vadym Denysenko said in televised remarks on Saturday. "I can say that we have lost this economic giant. In fact, one of the largest metallurgical plants in Europe is actually being destroyed.''
Zelenskyy said in his Friday nighttime video address to the nation that more than 9,000 people were able to leave Mariupol in the past day, and in all more than 180,000 people have been able to flee through humanitarian corridors.
The Russian military reported Saturday that it has used its latest hypersonic missile for the first time in combat. A spokesman for the Russian Defense Ministry, Maj. Gen. Igor Konashenkov, said Kinzhal missiles destroyed an underground warehouse storing Ukrainian missiles and aviation ammunition in the western Ivano-Frankivsk region of Ukraine.
Late Friday, Ukrainian officials said that Mariupol lost its access to the Azov Sea, which is connected to the much larger Black Sea.
Shelling continued at the edges of Kyiv on Friday, while a barrage of missiles was launched against an aircraft repair installation at an airport outside the western city of Lviv, close to the border with Poland.
Ukraine said it had shot down two of six missiles launched in the attack from the Black Sea, which killed one person. The early morning strike was the closest one yet to the centre of Lviv, which has become a crossroads for people fleeing from other parts of Ukraine and for others entering to deliver aid or join the fight.
MEANWHILE, IN OUTER SPACE
Three Russian cosmonauts arrived Friday at the International Space Station, and as they floated into it in zero gravity, they were wearing bright yellow flight suits with blue accents. Those are the colours of the Ukrainian flag.
Later, the cosmonauts were able to talk to family back on Earth, and cosmonaut Oleg Artemyev was asked about the flight suits. He said every crew chooses its own flight suits and "in fact, we had accumulated a lot of yellow material so we needed to use it. So that's why we had to wear yellow.''
Since the war started, many people have used the Ukrainian flag and its colours to show solidarity with the country. It was unclear what message, if any, the yellow uniforms were intended to send.
WHAT ARE WORLD LEADERS DOING?
President Joe Biden and China's Xi Jinping spoke Friday for nearly two hours via video as the U.S. looks to deter Beijing from providing military or economic aid for Russia's invasion. Biden described the consequences the Chinese would face from the U.S. if they provide military or economic assistance for Russia's invasion of Ukraine. White House Press Secretary Jen Psaki declined to detail possible consequences but a senior administration official said Biden pointed to the economic isolation that Russia has faced.
For his part, Xi urged the U.S. and Russia to negotiate and blamed the U.S. for the crisis
French President Emmanuel Macron pressed for an immediate cease-fire in a phone call Friday with Putin. Macron's office said Putin laid the blame on Ukraine. German Chancellor Olaf Scholz also pressed Putin for a cease-fire in a Friday conversation.
Biden plans to travel to Europe next week for talks with European leaders about the Russian invasion, and will attend an extraordinary NATO summit in Brussels.
WHERE DO RUSSIAN-UKRAINE TALKS STAND?
The head of the Russian delegation in talks with Ukrainian officials says the parties have come closer to an agreement on a neutral status for Ukraine, one of the key Russian demands as its offensive continues. Vladimir Medinsky said Friday that the sides also have narrowed their differences on the issue of Ukraine dropping its bid to join NATO.
But Mikhailo Podolyak, an adviser to Zelenskyy, tweeted: "Our positions are unchanged. A ceasefire, withdrawal of troops & strong security guarantees with concrete formulas."
WHAT IS THE CIVILIAN TOLL IN THE WAR SO FAR?
The U.N. human rights office says that it has recorded a total of 816 civilians killed and 1,333 injured since the fighting began on Feb. 24, though it only reports counts that it can verify. It believes the figures vastly understate the actual toll. Ukrainian officials say thousands have been killed.
WHAT HAS THE AP DIRECTLY WITNESSED OR CONFIRMED?
Since the start of Russia's invasion of Ukraine, AP journalists are relaying images of destruction, distress, and defiance from across the country.
A soldier standing guard near the site of the strike in Lviv said he heard three blasts in quick succession around 6 a.m. A nearby resident described his building vibrating from the explosions and people panicking. Smoke continued to rise from the site hours later.
HOW IS THE WORLD RESPONDING TO THE WAR?
The United States and its allies have put a slew of sanctions in place aimed at crippling the Russian economy. Hundreds of international companies have announced that they are curtailing operations in Russia, and those who remain are under pressure to pull out.
Pope Francis on Friday denounced what he called the "perverse abuse of power'' in Russia's war in Ukraine and called for aid for Ukrainians whose identity, history and tradition are under attack. Francis' comments were some of his strongest yet in asserting Ukraine's right to exist as a sovereign state.
Aid agencies are ramping up their efforts to deliver relief supplies to civilians affected by the fighting and refugees who have fled Ukraine. The Polish city of Rzeszow, about 60 miles (100 kilometres) from the Ukrainian border, has become a humanitarian hub for the region.
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