This is strange. The Ukrainian news I saw yesterday made it sound like the breakout from Normandy. I guess not?
Why, sir, these "slivers of land" are far, far bigger than anything in WWII, We have the enthusiasts to thank for this clarification ( < s a r c > ).
As the BBC notes, "Ukrainian forces say...."
Wiki states, "In military strategy, a bridgehead (or bridge-head) is the strategically important area of ground around the end of a bridge or other place of possible crossing over a body of water which at time of conflict is sought to be defended or taken over by the belligerent forces."
If the BBC report is to be accepted, then "The few hundred soldiers are outnumbered and surrounded in three directions, yet have managed to dig in for the best part of a month. This isn't the thousands needed to potentially liberate swathes of territory which Kyiv so desperately wants to do."
Not a "bridgehead" for a native English speaker.
An interesting aspect to this is the "provenance" of the information. "Ukrainian forces say" → BBC → MSN.
Reading to the bottom of the article ---
From his position, as a rank-and-file soldier on the front line, Denys has seen a horrifying human cost on his own side of the incremental breakthroughs in recapturing territory. "The commander throws anyone - cooks or drivers - into the furnace. They simply die there in their hundreds.""Those commanders will have to be arrested and tried after the war," he says.