Militarily, Russia has proven to be weak and ineffective against a country that, theoretically, they should have over-run in a couple of weeks. Even so, military conquest doesn't come with the right to annex territory. In this case it was aggression, pure and simple, and to give them an inch of territory would be to give in to the bully. There is no reason to do that. Even in Luhansk and Donetsk, in the Donbas region, where there is a larger Russian=speaking population than anywhere else in Ukraine, the referendum showed a majority of the population preferred to be free under Ukrainian government than to not be free under the Russian dictatorship.
The boundaries of Ukraine, which were established and recognized internationally within a few months of its independence declaration, are also supported historically and traditionally as a province under the Czar, and then as one of the Soviet republics. This included Oblasts in the west, around Lviv, Ternopol, Lutsk, Vlodomir, and Uzhhorod, taken from Poland by the Soviet Union and compensated by the Soviets taking territory east of the Oder River, including Silesia and East Prussia, that had been part of Germany, and giving it to the displaced Polish population. Being under Ukrainian rule must have its advantages, since most of the Moldovans, Slovaks, Hungarians, Poles and Romanians who make up the minority ethnicities in the Ukrainian west vote in high percentages to support the national government. So, apparently, does the Russian minority.
If Russia is not made to provide reparations for the damages to Ukrainian property they inflicted, the bully wins. That's how it goes.
The US, backed by European Union and NATO, could draft a treaty requiring Russia get out of Ukraine, guarantee the peace and provide compensation for damages with not a lot of fuss. Pull the plug and make sanctions work, instead of letting Russia get around them, and they'd be at the negotiating table in less than a week. The threats would stop and Russia, snarling and grumbling, would leave
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