// BBC WORLD NEWS — MONDO
Ukraine's fortress cities under fire as Russia bids to seize rest of Donbas
Residents sit in front of a Kramatorsk apartment block damaged by a Russian strike
It is so dangerous now in Slovyansk and Kramatorsk that police say it is time for civilians to get out. These neighbouring cities are the biggest still under full Ukrainian control in the eastern Donbas region.
In the worst affected areas, forced evacuations of families with children have already begun, says Pavlo Dyachenko of Donetsk police.
"This is the only way to save your life," he says, because security has deteriorated so much.
"If you take Slovyansk, it used to be hit by glide bombs roughly once a week, but now it's almost every day."
Slovyansk, Kramatorsk and Kostyantynivka, to the south, form part of what is known as Ukraine's "fortress belt" – a system of heavily reinforced defence lines in the east.
However, Kostyantynivka only has a limited presence of Ukrainian troops left, reports say, while Russia claims to be in full control of it.
The full capture of Donbas, made up of the Donetsk and Luhansk regions, is a key objective for Russia. Moscow has often cited the "liberation" and "protection" of the predominantly Russian-speaking Donbas as justification for the full-scale invasion of Ukraine.
The Russian army already controls almost all of Luhansk region, and is now in control of almost 80% of Donetsk region too, where all three fortress cities lie.
For the past few months, the territory near Kramatorsk and Slovyansk has been the main focus of Russian ground assaults. Capturing them would potentially make it much easier for Russia to advance to the west.