[Right_Wing_Madman]

why has Putin taken the drastic step of mobilization?

Putin put limitations on the original SMO because he wanted an early negotiated settlement with Ukraine. And the plan almost worked! On March 29th in Istanbul, Ukraine presented a peace proposal (concession of Crimea and Donbass, no NATO, no nukes), but quickly withdrew it at the urging of the US State Department (the ghoulish Victoria Nuland had not seen enough dead bodies yet and she did not want her pet project subverted). Russia was furious at the retraction, broke off negotiations, and continued the SMO. Russia then learned after Ukraine's counteroffensive in September that objectives in Ukraine would have to met with a larger force and less restrictions (Plan B). Before the war began, Putin knew Russia had the resources to escalate the fighting and end the war in Ukraine on more severe terms, if necessary.

[Rockingham]

Yes, all is going well for Russia in its attack on Ukraine. That is why draft eligible Russian men are fleeing the country if they possibly can. That is why even the formerly supine Russian media and public are now critical of the war. That is why Putin and his gang are issuing nuclear threats.

More realistically, Russia and Putin are in a bind. Putin's amateurish war plan foolishly assumed that Ukraine was a pretend country that would quickly collapse, that the Russian military was competent and well-organized, and that the US and NATO would stand by and do nothing.

As it is, the Russian economy is beginning to collapse due to sanctions. Mobilization will do little more than send masses of unmotivated, poorly trained, and ill equipped Russian men to their deaths. Ukraine will continue to have the benefit of US and NATO support and push the Russians back. In a matter of months, less than a year, Putin will be dead or otherwise out of power, with a new government installed that will sue for peace and hope to hold Russia together.