The reason the Russians haven't caused more damage is because they thought they could topple the government quickly and install their own politicians, making Ukraine another Belarus.  Now they are changing tactics to destroy infrastructure and gain ground in the south to prevent Ukraine from having a sea route for goods, effectively allow Russia to control exports.  

Even if Russia withdraws, it will take years for Ukraine to rebuild and they won't have enough money to rebuild their military.  It's a lose-lose situation for everyone.

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