Thread by @TheStudyofWar

Russia’s southern defense is multilayered w/ each layer consisting of multiple lines of field fortifications.

Ukraine has penetrated the third & final line of the defensive layer near #Verbove, not the final line in Russia’s total defense in depth on the southern frontline.🧵1/9

https://twitter.com/TheStudyofWar/status/1705035277851414703

2/ The Russian network of field fortifications in Zaporizhia Oblast is a defense in depth spanning 20-30 km deep, depending on the area of the front.

Ukrainian forces have advanced through approximately 8km in the Robotyne - Verbove area since June 2023.

3/ The inflection ISW reported on September 21 is that Ukrainian forces have deployed infantry fighting vehicles beyond a major triune belt of the best-prepared field fortifications on the Robotyne-Verbove line.

4/ This triune military engineering obstacle has three (mostly) contiguous layered components:

-An anti-vehicle ditch
-Dragon’s teeth obstacles
-Fighting positions (prepared trenches for infantry)

5/ ISW’s September 21 report stated that “Ukrainian armored vehicles are operating beyond the final line *of the Russian defensive layer that Ukrainian forces in western Zaporizhia Oblast are currently penetrating.*”

6/ ISW’s report was in reference to the fighting positions – the third and final component of this particular tri-layered military engineering obstacle – not the final field fortification in Russia’s total defense in depth on the southern frontline.

7/ Ukrainian forces can break through the final component of a larger coherent obstacle without breaking through all Russian obstacles in depth.

8/ ISW’s maps have consistently shown the depth of observed Russian field fortifications in southern Ukraine and informed readers likely to understand the context that there are more field fortifications beyond the line that Ukrainian forces are currently penetrating.

9/ UKR forces still have much territory to maneuver through, but the Ukrainian breach of this line is nevertheless very significant.

To reiterate yesterday's report, ISW is “not yet prepared to assess that Ukrainian forces have broken fully through this Russian defensive layer.”