Phase 2 of Russia's Ukraine offensive - military notes.

Ukraine's 603,628 square kilometers (2,782 kilometers coastline) comprises two different biomes (bio-geographic areas): mixed forest towards the middle; and steppe towards the Black Sea littoral interspersed with lowlands, uplands plateaus and basins.

Mostly part of Great European Plain, Ukraine's fertile steppes/plateaus are crossed by Dnieper, Seversky Donets, Dniester and the Southern Bug Rivers, emptying into Black Sea and the smaller Sea of Azov. Danube River delta in the southwest forms its border with Romania. Besides, Carpathian Mountains in the west and Crimean Mountains in the extreme south along the coast (of no military consequence in this war), the only formidable obstacle to military movement is the forested, riverine terrain and wetland north of Kyiv (Pripyat and Pinsk Marshes).

Once frozen in winter (up to February), this marshland makes Kyiv vulnerable to any attack from Belarus, a mere 56 kilometers north, as the frozen wetland supports military traffic. Spring thaw and the ensuing low bearing capacity due to mud, converts it into formidable obstacle that significantly hindered the Russian offensive against Kyiv. The 1,600-square-kilometer Chernobyl Zone (the site of 1986 nuclear disaster) also restricts movements along this Axis due to residual radioactivity.

Dnieper River compartmentalises any north-south military offensive into eastern and western halves. Donbas region's military geography (pro-Moscow separatists) supports Russian military effort from the east, as Russian Army reoriented during the 2nd/current phase of their operations. Sprawling Ukrainian cities/towns pose attacker with a predicament. Mere investment (encirclement) ties down significant forces, let alone clearance that requires a 9:1 numerical superiority over the defender.

Russia's westward advance from Donbas could be held up by Ukraine inundating ground, after blowing the massive dam on Dnieper near the southern city of Zaporizhzhya (also causing damage to its people), like Stalin did to the advancing German forces in World War II.

Black Sea and Sea of Azov in the south are Ukraine's only sea lines of communications. Russia's 2014 annexation of Crimea provides it expanded access to the sea. However, Russo-Ukrainian maritime trade, and Black Sea Fleet's outside forays (supply of rotational troops in Syria through Mediterranean) depend upon Turkish goodwill. Russia did construct a 20-kilometer-long bridge over Kerch Strait (connecting Black Sea and...