How might Russia act to show support for East Ukraine

[Reality Check]

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The Kiev government is taking military action against Russia's allies in Eastern Ukraine, as a warning to Russia, and as a warning to Russia's allies in Ukraine, before the diplomatic talks on Thursday.
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Russia could just complain - which will make it look weak, like the west looked weak when a bloodless military action was taken by Russia, and Russia's allies, within Crimea.
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Russia could take drastic economic action against Ukraine directly, and the west indirectly, such as shutting off both gas lines to Ukraine, and shutting down the border between Ukraine and Russia, to trade between Ukraine and Russia. Such action would devastate the entire Ukrainian economy overnight.
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Both of the above moves by Russia would severely hurt Russia's allies in Ukraine, the very people Russia claims to be the protector of, as well as the Russian economy.
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Russia could start a war inside the neighborhoods of Ukraine where Russia's allies in Ukraine live ( Eastern Ukraine ).
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Or, Russia could launch preemptive military attacks on the homes of the leaders, of certain factions, in the current Kiev government, the factions Russia wants to make appear to be weak and dangerous terrorists. These could be justified in the same way Kiev is justifying it's attacks in Eastern Ukraine. The same way the United States justifies it's military strikes against individual leaders of terrorist groups ( even when women and children are killed as collateral damage). Russia would be bringing justice to the terrorists who overthrew the legitimately elected government of Ukraine using violence, and bringing justice to the terrorists who are sending their armed men to the Russian speaking areas of Ukrainian, to kill Russian speaking citizens of those areas in Eastern Ukraine.

Only the last action does not appear to be an action of weakness, or an inaction of weakness, on Putin's part.

The last would send a warning message to the leaders of the swing factions in the Ukraine's current government that were not attacked, that any armed conflict will not be fought on the portion of Ukraine where Russia's allies live.