Russian troop build-up threatens city seen as key to seizing Ukraine's Donbas

What we know

If Kostyantynivka falls, Russian forces would be able push towards Ukraine's last remaining strongholds in the east

What changes

BBC highlights this story because it changes the calculus for actors watching russian, troop, build, threatens, city.

The setting

Earlier reporting from BBC and comparable outlets sketched the conditions that would eventually produce an event like this.

Where this fits in Signal Ledger

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Signal Ledger on russian

Signal Ledger reads this through the lens of russian, troop, build, threatens, city: If Kostyantynivka falls, Russian forces would be able push towards Ukraine's last remaining strongholds in the east.