Russia-ukraine war: Key things to know about the conflict

Russian troops are pressing their offensive across Ukraine, pounding populated areas with artillery and airstrikes and deploying siege tactics honed in Syria and Chechnya — where front line cities were reduced to rubble.

The port city of Mariupol was again a focus of intense shelling Saturday, with Russian forces striking an area around a mosque that was sheltering more than 80 people, including children. There was no immediate word of casualties from the shelling surrounding the mosque.

Bombardment intensified as Russian units fanned out to prepare their assault on Ukraine’s capital, Kyiv, a major political and strategic prize for Russian President Vladimir Putin.

Ukrainian President Volodymyr Zelenskyy said Russia would need to carpet-bomb Kyiv and kill its residents to take the city, and he encouraged his people to keep resisting.

“They will come here only if they kill us all,” Zelenskyy said. “If that is their goal, let them come.”

Now in its third week, the war has expanded to areas in western Ukraine, closer to NATO members Poland and Romania. Meanwhile residents in some besieged areas have faced so much firepower they can’t even bury the dead. The war has forced more than 2.5 million people to flee Ukraine. The Ukrainian chief prosecutor’s office says at least 79 children have been killed since the invasion began.

Here are some key things to know about the war:

WHAT’S HAPPENING IN BESIEGED MARIUPOL?

The Ukrainian government said a mosque in the city’s center was shelled, but an unverified Instagram post by a man claiming to be the mosque association’s president said the mosque itself wasn’t hit, but a bomb fell about 750 yards (700 meters) away.

The Ukrainian Embassy in Turkey said 86 Turkish nationals, including 34 children, were among those who had sought safety in the mosque.

Ukrainian authorities have warned of a humanitarian catastrophe in Mariupol, besieged by Russian forces and where Ukraine’s military said Russian forces have captured the city’s eastern outskirts.

Repeated attempts to bring in food and evacuate civilians have been cancelled due to relentless Russian fire. Zelenskyy said Russians are bombing the city 24 hours a day, while Moscow accuses the Ukrainians of violating cease-fires.

Mariupol’s mayor says the 12-day assault has killed over 1,500 people.

Doctors Without Borders said some residents are dying for lack of medication, with the city without drinking water or medicine for over a week now. The aid group says people are resorting to boiling water from the ground or extracted from heating pipes.

WHAT HAPPENED TO THE MAYOR OF MELITOPOL?

Zelenskyy has accused Russia of kidnapping the mayor of the occupied city of Melitopol, west of Mariupol and near Crimea, calling it “a new stage of terror.”

Kirill Timoshenko, the deputy head of Ukraine’s presidential office, posted a video which he said shows armed men taking Mayor Ivan Fedorov across a square. Russian forces captured Melitopol, with a population of 150,000, on Feb. 26. The video could not be immediately independently confirmed. Another video subsequently published online showed hundreds of Melitopol residents marching in a central square, demanding the mayor’s release.

The prosecutor’s office of the Luhansk People’s Republic, a Moscow-backed rebel region in eastern Ukraine, accused Fedorov on its website of “terrorist activities.”