Given the success it enjoyed in Crimea and Syria, the most striking surprise of the Ukrainian war thus far is the sub-par combat performance of the Russian Army.

While Moscow’s special forces displayed impressive form in the former conflicts, the current struggle is exposing major chinks in the armor of its main-force units. As a result, the critics have been out in force.

Widespread critiques of Moscow’s campaign plan have flailed its mistaken intelligence assumptions and multiplicity of objectives. The failings of the Russian Army’s signals and logistics systems, and the incompetence and low morale of some of its troops, have also come in for withering criticism.

But a more structural problem is becoming apparent. While Russia is deploying fearsome artillery and massive weight of armor in Ukraine, it is coming up short in the central combat arm of any army: infantry.