Can Russia reconstitute its forces in Ukraine?

 ISW:

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Russia may be weakened but the Kremlin’s intent regarding the US and NATO remains the same. Russia not only seeks to eradicate Ukrainian statehood, but also to control other states in the region, such as Belarus and Moldova, and eventually link Russian military gains across the former Soviet Union.[11] Putin still seeks to neutralize NATO and undermine the US. The Kremlin is rallying Russian society for a long fight against the West.[12]

The future of Russia’s power and the Kremlin’s ability to act on its unchanged intent regarding the US and NATO disproportionately depends on Russia’s gains or losses in Ukraine. If Russia loses gains in Ukraine, many of Russia’s already limited bases of power will further diminish.[13]

The US should not underestimate Russian capabilities in the long term, however. If Russia keeps its gains in Ukraine, the Kremlin will have a chance to reconstitute its forces, to launch future attacks against Ukraine, and to connect its military gains in Ukraine and Belarus. This would mean massive military and economic requirements for the US, NATO, and EU. And when Russia attacks Ukraine again, the US will have the same obligation to support its NATO allies, who are threatened by any war in Europe.

Russia keeping its gains in Ukraine will increase the risk of other states using nuclear blackmail. Any peace deal with Russia in which the Kremlin keeps gains in Ukraine would imply that the West yielded to Russia’s nuclear blackmail. It would hurt, not help, the US in its competition with China, as China would certainly internalize this lesson.

The US thus risks facing the same problem with the same escalation risks but under worse conditions if it does not help Ukraine liberate its people and territory through a series of successive counteroffensive operations.
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Additionally, this war cannot be resolved through typical negotiations. Putin has resorted to a full-scale invasion of Ukraine when other means to control Ukraine failed. The Kremlin is engaged in a genocidal effort, aimed to eradicate Ukrainian identity and statehood through a large-scale mechanized invasion.

The US and the West should instead reorient their defense production to resource Ukraine’s successive counteroffensive operations and — critically — help Ukraine plan for a sustained force regeneration effort. This requires recognizing the necessity of an upfront investment to secure US long-term national security interests. Enabling Ukraine to achieve a decisive victory faster is a better investment than allowing — through either lack of action or pressuring Ukraine into concessions — Russia to pursue the long war that is the Kremlin’s likely best chance of achieving its maximalist objectives in Ukraine.

The task of Russia reconstituting its conventional forces is significant.  In the engagement in Ukraine, the Russians have expended around 70 years' worth of mechanized forces.  This has happened as the West has provided modern mechanized machinery to Ukraine.  Russia is a much weaker force than it was perceived prior to its latest war in Ukraine.  It may be able to mobilize more troops to replace its combat losses, but equipping them should be a challenge.