Because the Russians have repeatedly made such claims, during the siege of Mariupol was the first. But there has never been proof presented.
Contrariwise, the Ukrainians have also often made such claims, almost always followed by Russian media death notices, funerals, etc.
Let see.
How about this proof?
Russkies.............
- Now control Mariupul
- Now control Bakhmut
- Now control Advikia
- Over 23% of former Ukieland
- Stopped the much-promoted and great Ukie offensive to drive the Ruskies into the Black Sea. Stopped them dead in their tracks
Tell us again, "It ain't so. You can't believe reality."
So, it's just Ruskie propaganda -- except it's not.